Michel Nabaa

Cyrille Bertelle

Antoine Dutot

Damien Olivier

Exploitation of a displacement survey to detect road network use vulnerability

Keywords: vulnerability, risk, self organization, detection of organizations, GIS, household displacement survey

Many agglomeration are faced to multiple technological and natural hazards. The use of the road network by vehicles may cause big problems especially under evacuation situations. An accident on a main road may endanger many lives. A household survey was conducted in CODAH 1 about people displacement in the seine estuary. In this paper, we extracted and treated the survey result. We also compared results with a detection of organizations in large graphs algorithm.

I. INTRODUCTION

A S many agglomerations, CODAH is faced to natural and technological hazards. 33 establishments are classified SEVESO 2 with high threshold. To minimize risk effects, we must localize the population at any time. In this context, the major risk management team (DIRM) of CODAH has developed a model to estimate the diurnal / nocturnal population distribution at buildings scale (PRET RESSE) [START_REF] Bourcier | Allocation spatio-temporelle de la population exposée aux risques majeurs. contribution à l'expologie sur le bassin de risques majeurs de l'estuaire de la seine: modèle pret-resse[END_REF]. This model does not take into account the population displacement on the road network. In previous works, we proposed an approach to dynamically assess the vulnerability related to the road network use by vehicles [START_REF] Bertelle | Modeling of the vulnerability related to the dynamic road traffic[END_REF], [START_REF] Bertelle | Detection of organizations in large graphs : Application on risk management[END_REF]. To complete this work, we have exploited a household survey about the displacement of the population of CODAH in the Seine estuary. In this paper, we exploit the survey and we compute vehicles path declared displacements to dispatch the population on the network. We present also a detection of organizations on large graphs algorithm. The aim of this algorithm is to detect zones susceptible to be congested, this by taking into account the topological aspect of the graph. Finally, the results of the survey will be compared to those obtained from the algorithm.

II. RISK MANAGEMENT

Real exercises in an evacuation planning are so expensive (people, resources, logistics...) and sometimes not realistic : they can not take into account each individual behavior as the panic effect and initial response to an evacuation in a dangerous area. Panic generally results from the lack of coordination and dialog between individuals. Hence the use of the simulation and in particular Multi-Agent Systems (MAS) is necessary to model each agent behavior and more understand the evolution of a critical situation due to interactions between evacuees and the propagation of a danger : an accident on the road network may cause dangerous traffic jams especially in a case of a danger that spreads quickly. Once we understand the evolution of a critical situation, we try to fight against organizations of vehicles and try to allocate vehicles on different roads to avoid bottlenecks. Recently, many researchers tried to couple a MAS with a Geographical Information System (GIS), especially in risk management and vulnerability assessment. For computer modelers, this integration provides the ability to have agents linked to real geographical locations. For GIS users, it provides the ability to model the emergence of phenomena by various interactions of agents in time and space by using a GIS [START_REF] Najlis | Repast for gis[END_REF]. Thanks to a GIS, one can combine different vulnerability layers (a layer per danger : geophysical one, social one, access to the network...) to construct a global layer which leads to a better assessment of vulnerability; we think particularly about the work of [START_REF] Cutter | Revealing the vulnerability of people and places: a case study of georgetown county, south carolina[END_REF]. In geography, the representation of a MAS coexists n levels of organizations and use several classes of agents (e.g. Level 1: individuals or companies, Level 2 and three: economic, urban communities).There will be rules at every level and the approach is not necessarily a bottom up one as in the models of self-organization [START_REF] Daudé | Systèmes multi-agents pour la simulation en géographie : vers une Géographie Artificielle[END_REF]. In [START_REF] Provitolo | A proposition for a classification of the catastrophe systems based on complexity criteria[END_REF], the author modeled the spread of the panic from a group of individuals in danger situation to non panicked ones. She used a dynamic system (differential equations) to simulate the behavior of individuals. Many execution scenarios showed that the emergence of panic has not occurred in all scenarios when changing some parameters. The emergence depends on the rate of transmission from a population susceptible to panic to a panicked population , the time taken to return to a normal behavior (the population is more panicked after the disaster) and the number of initially panicked people. The principle of resilience was also discussed; it represents the time that the system makes to return to its initial state after a period of instability due to a disaster.

At neighborhood scale, many researches where developed models based on microsimulation. In their paper [START_REF] Church | Mapping evacuation risk on transposion networks using a spatial optimization model[END_REF], the authors have presented a model to estimate the time required to evacuate a neighborhood according to the population, the number of vehicles and roads network capacity. The model is based on optimization in order to find the dangerous area around a critical point. This model was coupled with a GIS (ArcInfo) to visualize the results (identifying evacuation plans) and to establish an evacuation map for the town (Santa Barbara). The same authors [START_REF] Cova | Modelling community evacuation vulnerability using gis[END_REF] opened the way to the study based on geographic information systems to evacuate people. Their study identified communities that may face transportation difficulties during an evacuation. They modeled the city by a graph to estimate lanes (Lane) occupation by vehicles during an evacuation. A graph partitioning model was adopted in order to detect vulnerable neighborhoods around each node of the graph and to build a vulnerability map around the nodes of the graph. A constructive heuristic was used to calculate the best cluster around each node. The result was displayed on a map with ARCINFO GIS. An area is increasingly vulnerable according to the number of evacuees per lane (number of people to evacuate in a neighborhood / number of exit roads). The author believes that the combining of an evacuation based vulnerability layer and a hazard one allows to build a general risk map, so we can explore the various issues related to risk. However, in this approach, we predefine the maximum number of nodes in a neighborhood, which may not always be realistic and does not take into account the traffic evolution during evacuation. Secondly, the city of Santa Barbara is not a typical example of urban metropolitan areas in the United States with an important population facing great difficulties during a evacuation.

III. DISPLACEMENT SURVEY

Lifestyles and travel practices are changing. Traveled distances have increased. New infrastructures have been established and new services are proposed: these developments must meet the expectations and new patterns of migration of our territory inhabitants. That is why a household displacement survey was conducted, with a standard model developed by the Center for Studies on networks, transport, urban planning and public constructions (the CERTU). The survey will pro-vide shared data on current displacement practices and their evolution.

A. Survey utility

The last displacement survey occurred in 1992 at Le Havre agglomeration. Over time, taken paths become more complex and new infrastructures exist; hence the need to a displacement survey to respond to the population expectations, this by :

• considering the travel conditions between the city and its catchment area of life: people come from further far away to work, study or consume.

• Interview people about their expectations for transport.

• defining the transport policy of the CODAH for the coming years: how to increase the use of public transport, where and how to adapt the supply, how to relate the supply of transport lanes with the rest of the territory, what are the new flows, new trends, future developments areas of housing and economy ... • promote environmental issues, defined in the law of Solidarity and Urban Renewal. Communities undertake increasingly the development of a sustainable mobility. In this work, the main utility of the survey is to localize the population on the network at any time of the day. This will help us to detect the congested areas and to estimate the vulnerability related to the road network use by vehicles.

C. Environment modeling

The road network is integrated as a layer in the Geographic Information System (GIS). From this layer, we extract the data by using the open source java GIS toolkit Geotools. This toolkit provides several methods to manipulate Geo spatial data and implements Open Geospatial Consortium (OGC) specifications, so we can read and write to ESRI shapefile format. Once data road network are extracted, we use the GraphStream tool [START_REF] Dutot | Graphstream: A tool for bridging the gap between complex systems and dynamic graphs[END_REF] developed within LITIS laboratory of Le Havre to construct a graph corresponding to the GIS network layer. This tool is designed for modeling; processing and visualizing graphs. The data extracted from network layer contains the roads circulation direction, roads id, roads type, their lengths and geometry.

The extracted multigraph G = (V, E) represents the road network where V is the set of nodes and E the set of arcs. We deal with a multigraph because we have sometimes more than one oriented arc in the same direction between two adjacent nodes due to multiple routes between two points in the Seine Estuary road network. GraphStream facilitates this task because it is adapted to model and visualize multigraphs. In the constructed multigraph:

• The nodes represent roads intersections,

• The arcs represent the roads taken by vehicles,

D. Compute vehicles paths

In our work, we must repatriate people having their personal vehicle on the road network. The main goal is to detect routes with high vehicles density. It helps us in the detection of organizations and estimation of the vulnerability related to the road network using. Generally, people tend to choose the shortest path in time when using their own vehicles. This assumption, which may seem audacious and even unrealistic, however, is found in almost all mobility models implemented in most countries since 1960 [START_REF] Banos | À la conquête de la fourmilière urbaine : quand le géographe se fait explorateur de mondes artificiels[END_REF]. For each person displacement from a centroid c1 to a centroid c2, we compute the shortest path between the two nodes by using A-Star algorithm. It has the advantage to be fastest than Dijkstra algorithm when using an efficient heuristic. The last is an exact algorithm which compute the shortest path between a source node to all other nodes in a graph. In future work, we will use the dynamic version of A-Star (D-star) to avoid congested routes when computing paths. Another problem occurred when defining just one centroid per zone; obviously the must connected one. In figure 4, taken routes by vehicles are colored in red. At the left of the figure, we adopt one centroid per zone : we have 4772 taken routes and those routes are quickly congested. At the right, we used 15 centroids per zone to overcome this limitation : 17684 routes was taken. It is the maximum centroids number per zone if we use a machine having 2GO of ram. We can conclude that the more routes are taken and the less maximum roads capacity is violated. We conducted a simple experiment using random walks inside the city road network, seen as a graph. In this experiment we take a given number of entities placed randomly on nodes of the city graph. Then we run an iterative loop where, at each step, these entities either traverse a randomly chosen edge or wait.

Each time an entity crosses an edge e ∈ E, a special variable e np (number of passes) bound to the edge is incremented. At the end of such a simulation, the number of passes on each edge by entities will therefore be stored in these variables.

The entities may either cross an edge or wait because the displacements must consider road traversing times. The time an entity waits is proportional to the average time used to travel on the corresponding road: for two edges of the same length, an entity will wait longer if the road is a city road than if it is an highway.

After an entity crossed an edge, it chooses the next edge to cross randomly, but do not consider any more the edge it came from. The edges the entity used are stored in a memory, and the entity tries to avoid reusing them. This memory is a FIFO stack and ultimately, roads in the memory are forgotten, so that the entity can reuse them later.

As the road graph we use is bounded, some roads on the border are cut. If an entity reaches such a dead end (or a real bag end), it "jumps" in another position in the graph, chosen randomly.

In the figure 5 we show one run of this experiment. We in fact did several runs with a varying random seed, and always obtained very similar results. Edges are colored using a color graduation going from blue (almost no pass) to red (a lot of passes) passing by green, yellow and orange. The scale is geometric. To pass from blue to green you have to double the number of passes, and to pass from green to yellow you anew have to double this number of passes.

There are as many entities as nodes in the network. After some setup, we set the entity memory to 40 nodes. We stop the algorithm when a given maximum number of passes is reached on one of the edges, here 4000. We chosen such a high number to ensure the exploration of entities is significant enough. Fig. 5: Random walks in Le Havre, blueish to greenish roads are less used and yellowish to reddish roads are the more used.

For a better understanding, the same results are shown on figure 6 with labels that help to locate roads. The road that are highly used are labelled and highlighted. They correspond to town centers and highways. The A29 and A13 are the two main highways passing by and going to Le Havre. The road labelled "main city entry" is one of the most used road when coming to Le Havre (due to the fact the city is a harbour and have its south and west sides bordered by water, and at the north a plateau ("ville haute") with smaller accesses. The "Breque" label indicates a very large interchange that is, for the same reasons, one of the most used section of road when coming to and leaving Le Havre. Fig. 6: Figure 5 with labels on important areas.

The number of passes found with this random walk is an indication of the roads in the network were vehicles are inclined to pass, due to the topology of the road graph. This can be an indicator on areas where vehicle will most probably pass often.

We also run this simulation anew, but with some roads removed. Namely, we removed the A29 and A13 highways, as well as the "main city entry". The figure 7 shows the result. These road "absorbed" a large part of the traffic, and therefore all the entities use a lot more other roads. The "Breque" interchange is completely saturated. This place is well known by Le Havre inhabitants for the traffic jams occurring in the morning and the evening when people go to or leave their work. "La Breque" is one of the mandatory road to use in order to leave or enter the city. If we run the same experiment on figure 8, but only disabling the "main city entry", the results are more similar to the one without any road removed. This may mean that this road could be removed and people redirected to adjacent roads without impacting largely the traffic.

V. CONCLUSION

We have extracted a household survey on the motorized population displacement in the Seine Estuary. For each displacement from a zone to another one, we computed a shortest path from a centroid of the first zone to a centroid to the other zone. We used an A-Star algorithm to do that. Results showed that the more we have centroids per zone, the more we explore more routes and the less we violate routes capacity. We also applied on the Seine estuary graph, a detection of organizations algorithm based on random walks. The last showed that we can predict the possibility to have traffic jams in some areas on the basis of the network structure, this without having any data on the traffic. In the near future, we will adopt a microsimulation of the traffic with the use of D-Star algorithm to dynamically compute paths and to respect the road capacities at any time.

Fig. 1 :

 1 Fig. 1: zoning the Seine estuary communes

Fig. 2 :

 2 Fig. 2: UML schema

Fig. 3 :

 3 Fig. 3: Extract the graph and compute vehicles path

Fig. 4 :

 4 Fig. 4: Taken routes with one centroid and 15 centroids per zone

Fig. 7 :

 7 Fig. 7: Random walks in Le Havre, with the A29 and A13 highways removed as well as the main city entry.

Fig. 8 :

 8 Fig. 8: Random walks in Le Havre, with only the main city entry removed.

COmmunauté De l'Agglomération Havraise: it groups 17 communes including Le Havre. The goal is to to develop many common projects in territory management, health and hygiene, public transport, risk management...

Directive SEVESO is an European directive, it lays down to the states to identify potential dangerous site. It intends to prevent major accidents involving dangerous substances and limit their consequences for man and the environment, with a view to ensuring high levels of protection throughout the Community.


Bérénice Bellina

Aude Favereau

Laure Dussubieux

T O Pryce

Krisztina Hoppál

Óc Eo and the Thai-Malay Peninsula early trading polities links between the last centuries BC-early centuries CE based on archaeological material evidence

niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Sites in the peninsula and limitations

Sites in the TMP that yielded evidence for long-distance involvement include port-settlements as well as sites from their inland and maritime hinterland [START_REF] Bellina | Southeast Asian Early Maritime Silk Road Trading Polities' Hinterland and the Sea-Nomads of the Isthmus of Kra[END_REF][START_REF] Bulbeck | Indigenous traditions and exogenous influences in the early history of Peninsular Malaysia[END_REF][START_REF] Christie | Trade and State Formation in the Malay Peninsula and Sumatra, 300 BC -AD 700[END_REF]. This paper focuses on the material from port-settlements only. Other sites further south include Khlong Thom and Thung Tuk in peninsular Thailand [START_REF] Chaisuwan | Early Contacts between India and the Andaman Coast in Thailand from the Second Century BCE to Eleventh Century CE, in Early Interactions between South and Southeast Asia: Reflections on Cross-Cultural Exchange[END_REF]) and sites in Kedah (Kuala Selinsing, Sungai Batu) in Malaysia. The latter is not dealt with as its industries is less well known to the authors. In the TMP, most complete data come from the Isthmus of Kra where the French Archaeological Mission in peninsular Thailand-Myanmar (FAMPTM) works since 2005 in collaboration with Silpakorn University in Thailand and the department of Archaeology and the university of Mandalay in Myanmar. The FAMPTM has a strong focus on industries that are analysed with the technological approach in order to reconstruct the "chaîne opératoire", i.e. "a series of operations transforming a raw material into a finished product" [START_REF] Cresswell | Techniques et culture : les bases d'un programme de travail[END_REF]. This enables reconstituting the technical traditions and the associated social group (Balfet 1991;[START_REF] Roux | Des céramiques et des hommes[END_REF][START_REF] Lemonnier | Mythiques chaînes opératoires[END_REF]).

Three periods can be distinguished for the exchange networks and within the sites of the TMP: the late prehistoric earliest sites which emerged in the late 5th and early 4th centuries, early ports from the 3rd-2nd centuries BC, during which trade intensified, probably in connection with the involvement of the Roman world and then China and the protohistoric and early Historical sites until the mid-first first millennium CE. Most of ports excavated or surveyed by the archaeological mission in the Isthmus of Kra have yielded material from an earlier period prior to the Óc Eo period (500-400 BC to AD 100), and from an "Early Óc Eo " period .

1.1. Late prehistoric -earliest sites -5 th -3 rd c. BC Khao Sam Kaeo (hereafter KSK) and Khao Sek (hereafter KK) (Chumphon Province of Thailand), Maliwan (Tanintharyi Region of Myanmar). Khao Sam Kaeo and Maliwan are currently the earliest cosmopolitan walled port-settlements in the TMP. There was found evidence for several craft productions involving the import of raw material (carnelian, nephrite, glass), the use of foreign skilled technologies and the likely presence of foreign artisans (Bellina 2017). Khao Sek appears smaller and possibly a satellite of Khao Sam Kaeo controlling one of the transpeninsular routes but also hosting similar crafts [START_REF] Dussubieux | Glass ornament production and trade polities in the Upper-Thai Peninsula during the Early Iron Age, in Bellina (ed.) The Late Prehistoric port-of-trade of Khao Sek (Chumphon province, Thailand) and its implications for the understanding of the early trade polities in Maritime Southeast Asia[END_REF][START_REF] Bellina | The Elaboration of Political Models in Maritime Southeast Asia and of Pan-Regional Culture: Contribution from Khao Sek Stone Ornament Craft System Study[END_REF]. Khao Sam Kaeo and Maliwan yielded imports from India and the South China Sea.

1.2. Early sites -3 rd /2 nd BC-1 st CE During this period, network seem to shift with a larger involvement of southern India, in parallel to the growing interest of the Roman world in the far East and of China in the South China Sea. Sites in the TMP include KSK, KK and Maliwan and Aw Gyi (Tanintharyi Region), Tha Chana (Surat Thani Province, not excavated). Similarly, craft production involving imported materials and foreign techniques are active. Besides raw materials from southern India can also be found more finished objects (beads and ceramics).

1.3. Protohistoric and early historical sites -mid-first mill. CE During this period, exchanges have increased with clearer involvement of the Middle-East and the emergence of sites further south in the peninsula such as Chaiya (Surat Thani Province), Thung Tuk [START_REF] Chaisuwan | Early Contacts between India and the Andaman Coast in Thailand from the Second Century BCE to Eleventh Century CE, in Early Interactions between South and Southeast Asia: Reflections on Cross-Cultural Exchange[END_REF], Khlong Thom (Krabi Province) [START_REF] Veraprasert | Khlong Thom: An Ancient Bead Manufacturing Location and an Ancient Entrepôt[END_REF][START_REF] Veraprasert | Khlong Thom: An Ancient Bead-manufacturing Location and an Ancient Entrepôt[END_REF]Bronson 1990) in Thailand and sites in Kedah sites in Kedah in Malaysia such as Sungai Batu [START_REF] Chia | Evidence of iron production at Sungai Batu, Kedah[END_REF].

Khlong Thom in the TMP has a long occupation or perhaps two periods of occupations during the first millennium. The site yielded several imports in the form of ceramics and raw materials and evidence for local workshops. There, craft involve more mass-production techniques and simpler morphologies and local adaptations of Indian and Western artefacts.

Map 1. sites in the Upper Thai-Malay peninsula mentioned in the text (FAMPTM) 1.4. Limitations TMP sites have been the subject of intense looting, some since the 1960s, such as Khlong Thom. Some have benefited from extensive and intensive excavations, post-excavation in-depth analysis and radiocarbon dating, such as KSK, KK and to a lesser extent Maliwan in Burma. This has made it possible to compare excavated data with data from other contexts and to reconstruct a rather robust cultural sequence. This is not the case for other late sites, such as Khlong Thom and Bang Kluay Nok. Also comparative studies are still limited to the earliest sites, to certain regions and types. Comparative studies between semi-precious stones (carnelian, agate), nephrite and glass ornaments were carried out for the earliest sites and far less for early historical sites. Ceramic studies were conducted thoroughly in the earliest sites of the TMP and compared with some regions. Certain types, such as the Sa Huynh-and/or Kalanay-related pottery [START_REF] Favereau | Interactions et modalités des échanges en Mer de Chine méridionale (500 avant notre ère -200 de notre ère) : approche technologique des assemblages céramiques[END_REF], the Fine Ware (Bouvet 2017) and later Han ceramics [START_REF] Perronet | Khao Sam Kaeo: an early portcity between the Indian Ocean and the South China Sea[END_REF]Yamagata 2007) are best known but the range of more discrete types constituting evidence of exchange between the two regions exist as this article hints and remain to be explored. Those types often are neither fully locals, nor fully imported, which may make it difficult to identify and interpret them. The study carried out in the TMP highlighted for instance the existence of a variety of hybrid ceramics made using local raw materials and exogenous morphologies. In some cases, technologies associated with those hybrid types are predominant while in other cases, they are unusual. As for ceramics of the early historical period, they need full investigation in the TMP.

Regional comparisons and future avenues for research by type of archaeological material

2.1. Ceramics -A. Favereau 2.1.1. Comparisons between TMP sites and Óc Eo Based on the ceramic data from analysis previously conducted in the Thai-Malay peninsula and on available publications on Óc Eo, various morpho-stylistic similarities have been spotted between both areas and are listed in the table below (table 1).

All types of ceramics mentioned in table 1 are poorly dated in the TMP, often lacking archaeological context, and the chronological range therefore lacks precision. Such vessels are usually found in limited quantity. All display forms rare in the TMP, that are not found at earlier periods. To clarify the chronology and better understand the networks in which communities of the TMP and Óc Eo were or were not involved, it may be useful to also list ceramic types documented in the TMP and in areas neighboring to Óc Eo, but which interestingly seem absent at Óc Eo . Several types are noted:

-Cups with high pedestal, which are documented in the TMP but also in the Mekong Delta at Giong Ca Vo for instance (Bouvet 2017). -"Black-and-Red Jars" (Bouvet 2017) which are identified in the TMP, in the Mekong Delta at Giong Ca Vo but also seem to be present further north at Hoa Diem (see Yamagata 2013: 125, fig. 52) and associated with dating ranging from 400 BC to AD 200. -"Kalanay-related pottery" which are reported in the TMP (Favereau, in press) and in Hoa Diem (Yamagata 2013). [START_REF] Bùi | ngoài trong văn hóa Óc Eo: nhận thức mới từ tiếp cận nghiên cứu so sánh (Foreign ceramics in Oc Eo culture: new perception from comparative research approach[END_REF], 2023) mentions the occasional occurrence of black polished ceramics in Óc Eo culture sites and suspects an Indian origin. Since the origin is not established yet, other comparisons might also be considered. For instance, those black polished ceramics seem to share some similarities with Kalanay-related pottery documented in the TMP, not only based on the visual aspect but also considering that these ceramics were tempered with organic materials. -"Fine Wares" from South Asia (Bouvet 2017), which are associated with dating ranging from 4th-1st c. BC. More and more "Fine Wares" have been identified in the TMP the past few years (Bouvet 2017;Lefrancq et al., in prep) and a few examples are reported in central Vietnam [START_REF] Glover | The Origins of Cham Civilization: indigenous, Chinese and Indian influences in Central Vietnam as revealed by excavations at Tra Kieu, Vietnam 1990 and 1993[END_REF].

Several scenarios are possible to explain why those ceramic types are not found in Óc Eo: (1) they may remain unidentified for the moment. [START_REF] Bùi | ngoài trong văn hóa Óc Eo: nhận thức mới từ tiếp cận nghiên cứu so sánh (Foreign ceramics in Oc Eo culture: new perception from comparative research approach[END_REF] notes, more research is needed to identify all exogenous ceramics in the Óc Eo culture. (2) They may relate to different periods -especially those that compare with ceramics at Giong Ca Vo (3) They may have travel along different networks and different routes.

Future avenues of research

To make progress on this topic in the future, it could be useful to carry out a detailed comparative analysis of all ceramic types (including locals) from the TMP and Óc Eo , considering ceramic raw materials, technologies, shapes, and decorations as well as archaeological contexts, with the following objectives: (1) to potentially identify more ceramics providing evidence of contact. Hybrid ceramics (i.e., ceramics incorporating local and exogenous elements), for instance, are often underestimated.

Those ceramics give the opportunity for in-depth investigations of stylistic and/or technological transfers between communities;

(2) to clarify the chronology and set up a techno-typo-chronological framework; and (3) to discuss the origin of ceramic types and characterize communities involved into contacts based on the ceramic data.

Type of ceramic showing similarities

Thai-Malay Peninsula Óc Eo

Clay stoves with "support pads"

(Khao Sam Kaeo, Tha Chana) (Malleret 1960, plate XXX) Possible decorative or architectural fragments (Aw Gyi, Khlong Thom) (Malleret 1960, plate XLV, T.4380) Lids with central grip knob (Khao Sam Kaeo, Maliwan, Aw Gyi, Khlong Thom) (Malleret 1960, plate LXVII, 2) Lids with central grip hole (Malleret 1960, plate XL, T.55) (Khao Sam Kaeo, Bang Kluay Nok, Khlong Thom) Kendis (spouted ceramics) (Khao Sam Kaeo, Maliwan, Chaiya) (Malleret 1960, plate XXXV, T.46) Fragments of spouted vessels are found on some of the TMP sites and at Óc Eo , but the Kendi shape itself was produced in South Asia before being introduced to Southeast Asia. It is a vessel shape identified at different time periods. Further analysis would be useful to clarify the origin of Kendis found in the TMP and Óc Eo , and to establish a detailed techno-typo-chronology. One specific Kendi shape is documented at Khao Sam Kaeo and Óc Eo : a globular spouted vessel with ringfoot. Base and body are impressed, and incisions of horizontal lines and broken lines can be found on the upper body.

Fragments of upper parts of kendis (Khao Sam Kaeo, Aw Gyi) (Malleret 1960, plate XLV, T.4820 & 4785) Impressed ceramics [START_REF] Malleret | L'archéologie du Delta du Mékong, Tome 2. La Civilisation Matérielle d'Oc-Èo[END_REF], plate XXIV, T.17) Impressed ceramics have been recovered from most of the sites in the Thai-Malay Peninsula. Such ceramics are also reported on various sites in the Mekong Delta including Óc Eo , but also further north in Hoa Diem for instance. The occurrence of impressed ceramics is documented in Óc Eo (Malleret 1959), but limited information is provided. Despite the ubiquity of impressed vessels in Southeast Asia and the fact that they are found at various time periods, such ceramics are often poorly documented. Analysis conducted in the TMP revealed a complexity that suggests that late Prehistoric impressed ceramics -and the people associated to them -may be classified into several groups and could have different origins.

Han-related ceramics (see Bùi Minh Trí 2022, illustrations 25-26) As highlighted by [START_REF] Bùi | ngoài trong văn hóa Óc Eo: nhận thức mới từ tiếp cận nghiên cứu so sánh (Foreign ceramics in Oc Eo culture: new perception from comparative research approach[END_REF], the presence of imported Han-related ceramics in the Mekong Delta and in the TMP may suggest links between both areas. In the Mekong Delta, two types of Hanrelated ceramics are reported: one imported from southern China and the other one from northern Vietnam [START_REF] Bùi | ngoài trong văn hóa Óc Eo: nhận thức mới từ tiếp cận nghiên cứu so sánh (Foreign ceramics in Oc Eo culture: new perception from comparative research approach[END_REF]. Interestingly, a similar situation is found in the TMP: Han-related ceramics were imported from different areas likely to be southern China on one hand and northern Vietnam on the other hand (this hypothesis is based on techno-morpho-stylistic comparisons between ceramics from the TMP, southern China and northern Vietnam [START_REF] Favereau | Interactions et modalités des échanges en Mer de Chine méridionale (500 avant notre ère -200 de notre ère) : approche technologique des assemblages céramiques[END_REF].

Table 1: similarities between ceramics from the Thai-Malay Peninsula and Óc Eo (pictures for Thai-Malay Peninsula ceramics: A. Favereau).

2.2. Glass -L. Dussubieux

Status of research on glass

As far as glass is concerned, mainland Southeast Asia has been studied quite unevenly. While certain regions have attracted a significant amount of attention such as Thailand and Cambodia (e.g. [START_REF] Dussubieux | Glass from an Early Southeast Asian Producing and Trading Centre ». In Khao Sam Kaeo: an early port-city between the Indian Ocean and the South China Sea, Bellina, Bérénice[END_REF][START_REF] Bellina | The Elaboration of Political Models in Maritime Southeast Asia and of Pan-Regional Culture: Contribution from Khao Sek Stone Ornament Craft System Study[END_REF][START_REF] Carter | Beads, Exchange Networks and Emerging Complexity: A Case Study from Cambodia and Thailand (500 bce-ce 500)[END_REF], other parts of SEA remained understudied, creating large gaps in the re-construction of the glass exchange network in this part of the world. Vietnam is part of the regions where there is still little data for ancient glass. Although glass beads of Óc Eo were recently discussed in [START_REF] Carter | Angkor Borei and protohistorical trade networks: a view from the glass and stone bead assemblage[END_REF], the material considered in that study was surface collected and lacked context limiting greatly conclusions.

Status of research on glass in the Mekong Delta:

-ancient sites: Giong Ca Vo yielded glass ornaments with a combination of potash and mineral sodahigh alumina (m-Na-Al) 3 glass [START_REF] Dussubieux | L'Apport de l'ablation laser couplée à l'ICP-MS à l'étude du verre archéologique de l'Océan Indien[END_REF] very similar to the glass pattern identified at other earlier sites such as KSK, KK but also Ban Don Ta Phet [START_REF] Dussubieux | Glass from an Early Southeast Asian Producing and Trading Centre ». In Khao Sam Kaeo: an early port-city between the Indian Ocean and the South China Sea, Bellina, Bérénice[END_REF][START_REF] Bellina | The Elaboration of Political Models in Maritime Southeast Asia and of Pan-Regional Culture: Contribution from Khao Sek Stone Ornament Craft System Study[END_REF]. This pattern was associated with a connection with the South China Sea network. As observed by [START_REF] Carter | Beads, Exchange Networks and Emerging Complexity: A Case Study from Cambodia and Thailand (500 bce-ce 500)[END_REF] this network vanished at some point (maybe at the end of the 1 st millennium BC) and was replaced by a different network with ramifications that extended westward toward Southeastern India that is visible at Óc Eo .

-early first mill. CE Several thousand beads were discovered at Óc Eo, spread over the entire site. The colors of the glass include ultramarine blue, turquoise or dark, pink or purple, red, yellow, green. Polychrome beads are black with white decorations (including Bird Star beads), others are black striped with red and white, or have an ocellated decoration. Gold (or silver) foil beads have been identified as well. The shapes of the beads are of a very wide variety: bi-conical beads, octahedral, ribbed spheroids, collared with sections of various shapes, hexagonal prism, cube without corner or tubular (Malleret 1962).

Local glass and bead manufacturing cannot be ruled out, but no kiln structure was found. However, many pieces of glass and slag were interpreted as evidence of bead making (Malleret 1962). Additionally, P. Francis Jr identified wasters and other artifacts among the material found at Óc Eo that suggest local production of monochrome drawn beads (Francis 2002:224). Regarding the availability of raw material sources, Óc Eo is in a sandy area, the site being located on the seashore. In Vietnam, there are, in certain coastal regions, sodic lands under the name of cat-loi that is similar to Indian reh that is used there for glassmaking [START_REF] Dussubieux | L'Apport de l'ablation laser couplée à l'ICP-MS à l'étude du verre archéologique de l'Océan Indien[END_REF]. The presence of Bird Star beads at Óc Eo (figure 1) seems to indicate a local origin for some of the beads. Elemental compositions of Bird Star beads (from unknown sites and contexts) published in [START_REF] Lankton | A study of mid-first millennium CE Southeast Asian specialized glass beadmaking traditions, in Interpreting Southeast Asia's Past: Monument, Image and Text[END_REF] suggest that recycled glass was used for their production, likely located in Southeast Asia. The same authors note the presence of these beads not only at Oc-Eo but possibly at Khlong Thom. They were also found in East Java (Adhyatman and Arifin, 1993). The site of Angkor Borei and more especially the Vat Komnou cemetery dating to 200 BC to 200 AD yielded 1320 glass beads that were mostly small monochrome drawn beads. Colors includes opaque red, yellow, orange, green, white, and black and translucent blues, purple, and turquoise blue. Most of the glass beads that were analyzed for elemental composition belong to the mineral soda -high alumina 1 (m-Na-Al 1) glass likely manufactured in South India. Smaller proportions of beads had a m-Na-Ca-Al composition. The origin of this glass type remains uncertain. A few beads with a soda plant ash composition typical of the Middle East while high lead glass beads with a Chinese origin indicate ties of Angkor Borei with long distance networks [START_REF] Carter | Angkor Borei and protohistorical trade networks: a view from the glass and stone bead assemblage[END_REF]).

-Glass and regional connections with special reference to the TMP and beyond The typology of the beads as well as the chemistry of the few specimens that were analyzed for compositional analysis testify of different types of connection of Óc Eo within Southeast Asia and beyond. The presence of gold or silver foil beads (figure 1) is generally associated with import from the Mediterranean world. The elemental analysis of a greenish glass chunk revealed a soda plant ash composition characteristic of middle eastern production. For further details on Mediterranean glass in SEA and between the TMP and Óc Eo , see dedicated section further below.

Most of the analyzed samples (that were small drawn monochrome beads) have a mineral soda -high alumina 1 (or m-Na-Al 1) composition that is a type of glass likely produced in Southeastern India and that is quite common starting around the first millennium BC in different part of Southeast Asia [START_REF] Carter | Beads, Exchange Networks and Emerging Complexity: A Case Study from Cambodia and Thailand (500 bce-ce 500)[END_REF][START_REF] Carter | Angkor Borei and protohistorical trade networks: a view from the glass and stone bead assemblage[END_REF]) including at the close by site of Angkor Borei in Cambodia. Although Óc Eo is a coastal site, [START_REF] Carter | Beads, Exchange Networks and Emerging Complexity: A Case Study from Cambodia and Thailand (500 bce-ce 500)[END_REF] notes that this glass type is more particularly abundant at sites located further inland based on her observation in Thailand and Cambodia. It is important to notice that glass data (including compositional analysis) is quite scarce for coastal sites contemporaneous of Óc Eo . A notable exception is Khlong Thom in peninsular Thailand; however, the data from these sites are unpublished.

The only site contemporaneous with Óc Eo on the TMP is Khlong Thom; however, the glass from this site that was studied for compositional analysis has no secure context. Besides, comparison between the two sites is difficult as more samples from KT were analyzed and they seem to be more diverse in typology (more polychrome beads, a gold foil bead…etc) at KT compared to Óc Eo. As a consequence, the composition at KT seems more diverse than in Óc Eo but this might be at least due to the (lack of) sample strategy at both sites. A few comments about the glass found at KT: m-Na-Al 1 glass are present at this site, but it is not as prevalent as it seems to be at Óc Eo. KT yielded m-Na-Ca-Al glass that is also found at Arikamedu, PKT and AG which show a strong Bay of Bengal component present at that site [START_REF] Dussubieux | Early glass trade in South and Southeast Asia: New insights from two coastal sites, Phu Khao Thong in Thailand and Arikamedu in South India, in: Crossing Borders[END_REF][START_REF] Dussubieux | First elemental analysis of glass from Southern Myanmar: replacing the region in the early Maritime Silk Road[END_REF] which is quite logical based on its location.

Future avenues of research

Compositional data for glass material from Vietnam with a secure context are extremely scarce making it difficult to understand the role of this region in Southeast Asian ancient glass exchange networks. It would be necessary to develop ancient glass analysis in Vietnam for sites dating from the second half of the 1 st millennium BC and onward. In parallel, we need more data for the rest of Southeast Asia for later periods (1 st millennium AD) as so far, more efforts were directed toward the Early Iron Age.

Semi-precious stones -B. Bellina

Semi-precious ornaments such as cornelian, agate, garnet, amethyst, are amongst the earliest evidence for exchanges with South Asia. In Southeast Asia, they appear simultaneously with glass.

Excavations of glass and stone workshops at KSK and Maliwan and studies of these ornaments there and in other sites such as KK seem to indicate that in SEA, their production network are linked together (Bellina and Bernard 2017;[START_REF] Bellina | The Elaboration of Political Models in Maritime Southeast Asia and of Pan-Regional Culture: Contribution from Khao Sek Stone Ornament Craft System Study[END_REF]. Similar observation was made in the case of Angkor Borei and inland communities forming part of its sphere of interaction [START_REF] Carter | Angkor Borei and protohistorical trade networks: a view from the glass and stone bead assemblage[END_REF]. Does this close association between the two production networks have anything to do with the organisation of production in South Asia, or rather with that of the trading cities of Southeast Asia, is a question for which we cannot provide an answer at present.

Bellina analysed stone ornaments:

-from the late prehistoric period, here Giong Phet, Giong Ca Vo, Phu Hoa, Sa Huynh in Vietnam in 2000 [START_REF] Bellina | Témoignages archéologiques d'échanges entre l'Inde et l'Asie du Sud-Est, morphologie, morphométrie et techniques de fabrication des perles en agate et en cornaline (VIe siècle avant notre ère -VIe siècle de notre ère)[END_REF][START_REF] Bellina | Cultural Exchange between India and Southeast Asia: Production and Distribution of Hard Stone Ornaments (VI c. BC-VI c. AD). Collection « Référentiels[END_REF] and from KSK, KK in the TMP (2001;2014;[START_REF] Bellina | The Elaboration of Political Models in Maritime Southeast Asia and of Pan-Regional Culture: Contribution from Khao Sek Stone Ornament Craft System Study[END_REF]. Their comparison showed that they share a similar style, skilled techniques used to produce high quality beads (figure 2).

-from protohistorical and early historical sites in the Mekong delta, sites in the Long An province (Nb: 45 from Go Hang, Go De and Go Dung) and Óc Eo (Nb: 76) with Nen Chua (Nb: 4) and Vong The (Nb: 10) in the vicinity and Khlong Thom in the TMP (Nb: 60) [START_REF] Bellina | Témoignages archéologiques d'échanges entre l'Inde et l'Asie du Sud-Est, morphologie, morphométrie et techniques de fabrication des perles en agate et en cornaline (VIe siècle avant notre ère -VIe siècle de notre ère)[END_REF]2007). On the basis of morphological and morphometric comparisons, perforation and polishing techniques secured by statistical tests, it was possible to characterise the Óc Eo technical system of which Vong The and Nen Chua belong. There is a style (techniques and morphologies) specific to the Óc Eo region that differs slightly from that of Long An and of course from other regional assemblages (Bellina 2001: 309). Although the evidence of production in the corpus examined is still patchy, based on the style and techniques, it seems clear that there were production workshops in the region that was distributed in neighboring areas.

Comparing the Óc Eo technical system with those of the TMP (figure 2): Some of the morphologies of the early prehistoric period can still be found during the later period but morphologies are generally simpler and mass production techniques predominate [START_REF] Bellina | Témoignages archéologiques d'échanges entre l'Inde et l'Asie du Sud-Est, morphologie, morphométrie et techniques de fabrication des perles en agate et en cornaline (VIe siècle avant notre ère -VIe siècle de notre ère)[END_REF]. Similar observation was made by Carter for beads at Angkor Borei and inland sites [START_REF] Carter | Angkor Borei and protohistorical trade networks: a view from the glass and stone bead assemblage[END_REF]. This is also the case for Óc Eo and Khlong Thom. They have in common that their morphologies are simpler than those of the ancient periods and that they are heterogeneous, with a few beads with more refined morphologies and finishes. This difference between the quality and techniques of beads from the ancient sites and sites of the protohistoric-early historical periods no doubt has to do with the wider use to which these beads were put over time. If contemporaneous, was the heterogeneity indicative of different social destinations? Unfortunately, the corpus studied in 2001 is too small and mostly devoid of context to allow to hypothesise about these social groups and their spatial distribution. In any case, the two regions show a similar trend in terms of production which probably reflects a comparable political and economic use of these industries in both regions [START_REF] Bellina | Témoignages archéologiques d'échanges entre l'Inde et l'Asie du Sud-Est, morphologie, morphométrie et techniques de fabrication des perles en agate et en cornaline (VIe siècle avant notre ère -VIe siècle de notre ère)[END_REF]. These well-contextualised and dated beads may thus constitute a solid base for comparative studies. They may even help refining the chronology for beads found in the TMP, especially for the critical period of the early historical period during which little research has been carried out on these industries. In this perspective, completing the technical system definition could be achieved with further technological analysis combining provenance analysis of the raw material and analysis of production technique. If associated with the provenance of glass such study would very likely provide major insights on regional connections. As mentioned before, in Southeast Asia, stone and glass production networks may be linked. Previous combined analysis of glass and stone technical systems and their evolution at Khao Sam Kaeo and at Khao Sek showed similar trends in the production, imports and shifts in network with connections with southern India during a later period. Similar combined and comparative studies across the South China Sea would surely provide further insights on the links between the two regions, perhaps even between some port-cities and their evolution through time. Such studies both at Óc Eo, at neighboring sites and with future excavations in the TMP at sites such as Bang Kluay Nok may provide further hints on differentiated products and their social destination, thus highlighting the structure in these early trading polities that were Óc Eo and those in the TMP.

Metals -T.O. Pryce and B. Bellina

The Mekong delta is devoid of the copper and tin minerals needed to produce bronze. Although speculative, it is conceivable that the conquest of the Upper TMP by Funan mentioned in Chinese texts (Pelliot 1903: 265), may have been in part stimulated by a desire to control the area's mineral resources.

Copper-based material

Unfortunately, the archaeometallurgical evidence for exchange between the TMP and Óc Eo is extremely limited; pertaining to vague stylistic and typological comparison (Pryce, Bellina and Bennett 2006, and below). This is due mainly to the absence, to the best of our knowledge, of any archaeometric analysis of copper-base artefacts from central and southern Vietnam, only a single study of gold and silver [START_REF] Schlosser | Early Cambodian Gold and Silver from Prohear: Composition, Trace Elements and Gilding[END_REF], and certainly not any lead isotope characterisations, which are the basis for effective provenance and network reconstruction research in Southeast Asia, as well as globally [START_REF] Pryce | Southeast Asia's First Isotopically-Defined Prehistoric Copper Production System: When Did Extractive Metallurgy Begin in the Khao Wong Prachan Valley of Central Thailand?[END_REF]2014;[START_REF] Killick | Geological Constraints on the Use of Lead Isotopes for Provenance in Archaeometallurgy[END_REF]. While this is remedied, we can at least evaluate the evidence for exchange between the Iron Age TMP and other contemporary assemblages from the coastal regions of Mainland Southeast Asia: namely Cambodia, southern Myanmar and northern Vietnam. Due to a super-abundance of data, and space limitations here, we will necessarily exclude inland Mainland Southeast Asia, except for known copper production loci, and Island Southeast Asia. Not including the latter is particularly artificial, as we are dealing with a largely maritime exchange space, but the reader should be aware that, to date, no archaeometric copperbase provenance data are available from Malaysia (nor Brunei, East Timor and Singapore) but we have preliminary, unpublished, data for Metal Age Palawan, Java and Sumatra, and published data for Bali (Pryce et al. 2018).

For the Southeast Asian maritime interaction sphere that concerns this paper, there are three principal typologies of interest: 'Indian' high-tin bronze bowls, 'Chinese' leaded high-tin bronze mirrors and 'Vietnamese' leaded bronze drums (not discussed here). The very thin hot-worked and quenched engraved high-tin bronzes were named 'Indian' due to their presence at Ban Don Tha Phet, an early Iron Age cemetery in central Thailand with 'Indian' hardstone ornaments [START_REF] Glover | Ban Don Ta Phet: The 1984-85 Excavation[END_REF]) and similar bowls on the Indian sub-continent [START_REF] Srinivasan | Wrought and Quenched, and Cast High-Tin Bronzes in Kerala State, India[END_REF]. Subsequently, typo-stylistically, technologically and elementally highly comparable examples have been excavated from KSK and Khao Sek in peninsular Thailand [START_REF] Pryce | High-Tin Bronze Bowls and Copper Drums: Non-Ferrous Archaeometallurgical Evidence for Khao Sek's Involvement and Role in Regional Exchange Systems[END_REF], Prohear in eastern Cambodia [START_REF] Pryce | More Questions than Answers: The Southeast Asian Lead Isotope Project 2009-2012[END_REF][START_REF] Reinecke | The First Golden Age of Cambodia: Excavation at Prohear[END_REF]) and even Bali (Pryce et al. 2018), as well as potential ingot from peninsular Thailand and West Bengal [START_REF] Pryce | More Questions than Answers: The Southeast Asian Lead Isotope Project 2009-2012[END_REF]). These artefacts, however, do not for the most part have compatible lead isotope signatures [START_REF] Pryce | More Questions than Answers: The Southeast Asian Lead Isotope Project 2009-2012[END_REF]. If none has been reported in the Mekong delta yet, it is not unlikely that future studies will identify these bowls that form part of the materials shared amongst early trade involved polities. The other 'maritime metal' class is that of leaded high-tin bronze mirrors, of Han stylistic origin. So far, the only Southeast Asian examples studied are from KSK, Sông Khoai in northern Vietnam and Pankung Paruk on Bali. The KSK mirror can be interpreted as a Western Han import, while those at Sông Khoai are Eastern Han and the Pankung Paruk example cannot, unfortunately, be attributed yet [START_REF] Pryce | More Questions than Answers: The Southeast Asian Lead Isotope Project 2009-2012[END_REF][START_REF] Bellina | The Elaboration of Political Models in Maritime Southeast Asia and of Pan-Regional Culture: Contribution from Khao Sek Stone Ornament Craft System Study[END_REF][START_REF] Pryce | The Metallurgical Industries[END_REF]. Many examples of these mirrors are known from central Vietnam (Yamagata, Manh, et Hoang 2001) but have not been archaeometrically studied, to the best of our knowledge. There is little doubt that southern Vietnam, and Óc Eo in particular, will have examples of all three copper-base metal classes, and potentially new ones, with which we can better characterise littoral interactions of the mid/late 1 st millennium BC and early/mid-1 st millennium AD.

Gold

Gold is widely, though irregularly, distributed throughout Southeast Asia in hard-rock (igneous and metamorphic) and placer (sedimentary) deposits (Gardner 1972: 333-343). The words 'gold' and 'golden' are often associated with place names throughout the region such as 'Golden Khersonese' of Ptolemy's Geography (Wheatley 1961: 144-147). Indian sources mention the Suvarnabhumi (Land of Gold) (Wheatley 1961: 177-184), possibly referring to lower Burma and the TMP, and the Suvarnadvipa (Islands of Gold) which may correspond to Borneo and/or Sumatra. Whether these terms refer to the metal or to those lands endowed with enriching resources is unclear. In the Upper TMP, gold lodes are known around Phuket and Prachuap Khiri Khan [START_REF] Sitthithaworn | Metallogenic Map of Thailand[END_REF]), 200-300km from KSK, but small local sources may have been exploited in the past. Comparisons are limited because gold artefacts are often melted when collected by villagers. However, a few artefacts show prehistoric and early historical links between the TMP and Mekong delta polities.

-Late prehistoric network related sites in Vietnam: KSK together with Giong Ca Vo, and the Tabon caves in the Palawan Island (Philippines) provide the earliest sites for the recovery of gold in maritime Southeast Asia (Fox 1970: 143). Provenance analysis of gold from Giong Ca Co showed that some were comparable to those from the TMP (Reinecke 2022). Central knobbed gold beads (Figure 6a), surface finds from KSK, share stylistic elements with several gold beads from Sa-Huynh related sites and especially at Giong Ca Vo in Southern Vietnam (Thang and Hien 1997: 41, Plate 17).

-Early Historical Óc Eo related sites in the Mekong delta: A gold pendent from KSK with filigree decoration from a private collection (Figure 6b) can be compared to a specimen from Óc Eo described by L. Malleret (1962: Plate V, n°757). The polyhedral/granulated gold bead from KSK (Figure 6c) is stylistically identical to other ornaments from Óc Eo (Malleret 1962 Links between the TMP and Óc Eo culture sites can also be examined through comparing the types, dates and distribution of Mediterranean and related finds discovered in these regions. The comprehensive database of Mediterranean imports produced between the last centuries BC and AD first centuries, and of Asia-produced inspired objects that are integrating Mediterranean elements (referred to as Mediterranean-inspired) consists of 73 entries referring to more than 150 individual objects from sites of mainland and island Southeast Asia (Hoppál et al. 2023).

The earliest sites dating from the fourth century BC -first century AD (KSK, Maliwan) and early sites dating from the last centuries BC (AG, BKN, PKT and TC) are all located on the Isthmus of Kra. Later sites dating from the early centuries AD or later can be found further south in Peninsular Thailand (KT and Thung Tuk). This is when Mediterranean related material is reported in the Mekong Delta at Óc Eo and Lung Lớn, Đá Nổi and Nền Chùa. Most of the materials, whether imported or inspired, come from the Kra Isthmus (32 out of 73) and Peninsular Thailand (24), then the Mekong region (12). Most of the Mediterranean imports came from the Kra Isthmus (28), and most of the Mediterraneaninspired objects came from later sites are in Peninsular Thailand (namely KT:14 entries out of 26), then from the Mekong Delta (7).

Isthmus of Kra vs. Óc Eo sites

Comparing the distribution of different Mediterranean and inspired materials from the Kra Isthmus and from OE sites, several differences and a few links can be inferred.

-Glass materials Most glass vessels of Mediterranean origin were found in the Kra Isthmus mostly from AG (4) and PKT (4). Those include multi-coloured and/or mosaic glass vessels dated to the first century BC -AD first century and undecorated fragments with a broader dating, from the first century CE to the fourth century CE. Mediterranean glass as a raw material has only been identified at AG, Maliwan and PKT (Hoppál et al. 2023). So far, one single entry of glass vessels is reported from Nền Chùa in the Mekong Delta. This entry is referring to transparent bluish and green fragments (Bùi Minh Trí et al. 2022: 317, fig. 196) of possibly Mediterranean origin, however further analyses would be required to define its origin. Glass beads of Mediterranean composition, particularly gold glass beads were discovered at PKT, TC and OE. Multi-coloured glass beads came from both regions, face beads of AD first century dating from Maliwan and KSK, and mosaic beads with a wider range of dating both from AG and OE-LL canal [START_REF] Dussubieux | First elemental analysis of glass from Southern Myanmar: replacing the region in the early Maritime Silk Road[END_REF]Bùi Minh Trí et al. 2022: 163, 165).

-Engraved gems Mediterranean imported engraved gems were discovered in both regions; however, those greatly differ in number, dates, and workmanship. Seven imported engraved gems mostly of high-quality with first century BC -AD first century dates came from early sites of the Kra Isthmus, from BKN, PKT and TC. The Mekong Delta yielded two Mediterranean engraved gems to date. Those include a red jasper intaglio depicting a chariot drawn by two mice, and with a cock as a charioteer possibly of AD second century date from Óc Eo. The other is a translucent green glass intaglio with the motif of a wreath discovered in Đá Nổi. Aquileia has also yielded an identical glass intaglio, which may even be from the same mould (Malleret 1962: Nos 1293and 1314, 299, 304, Plates LXVIII, LXXII;Middleton 2005: 17).

Map 2. Distribution of engraved gems in Southeast Asia (map B. Pradier)

-Inspired engraved gems The Kra Isthmus and OE yielded similar number of inspired engraved gems four from each region. In the case of the Isthmus, two came from BKN and two from PKT, and are typically AD first century dates, such as a carnelian intaglio depicting Herakles from PKT (Borell 2017b;Hoppál 2022: 206, fig. 3,1a-b). This might have been made in Gandhara, just like two of the four inspired engraved gems from Óc Eo (Malleret 1962: 295-296, 298,). However, in contrast to the PKT Herakles, the Óc Eo pieces have AD post-third century tentative dates. In the case of the other two inspired engraved gems from OE, tentative dates and production places are more complicated to define (Malleret 1962: 296;Hoppál 2022: 207).

2.5.2. Peninsular Thailand vs. Óc Eo sites Sites from P. Thailand and the Mekong Delta are all later in date and share more similarities regarding Mediterranean imports and inspired objects. Besides gold glass beads mentioned above, some degree of links between imported engraved gems can also be seen, although KT yielded a greater number (8 vs. 2) with more diverse dating (from the CE first century to the CE second-third century). Both KT and Óc Eo yielded engraved gems moulded in glass.

-Inspired engraved gems Number of inspired engraved gems is also the same in the case of P. Thailand and Óc Eo (4 vs 4). There are three yet-unexamined engraved gems were reported from KT and one from TT, all made of carnelian. Carnelian was used in case of the Óc Eo -discovered specimens as well. However, inspired engraved gems from P. Thailand seems to feature somewhat inferior quality and less-skilled workmanship compared to the Gandhara-connected OE pieces. This might suggest that the KT and TT inspired engraved gems might have been made locally or regionally. -Coin adaptations KT yielded several coin adaptations (9 entries: 18 pendants and a stone mould), while three came from Óc Eo. Some of the KT types might have been manufactured locally even by Indian craftsmen (the tin pendant evoking coin designs of Tiberius PONTIX MAXIM type coins). The pendants made of gold sheet and discs with relatively faithful representations partly or entirely derived from coins of the Antonine Dynasty came both from KT (4) and Óc Eo (2). These pendants of CE post-second century dates generally differ from the Indian coin copies and might be the results of local developments (Borell 2014: 27-29). Based on technical details, at least one of the gold pendants from Óc Eo can be closely connected to the KT found ones, suggesting yet another evidence of exchange between the two sites (Borell 2017d: 170). A single gold sheet pendant crudely evoking Roman coin design came from Óc Eo. This, as well as a similarly crude piece from UT, might be result of later simplification or mass production. KT also yielded four fifth-sixth century AD gold coins recalling Roman coins on the obverse that were intended for trade transactions [START_REF] Revire | Viṣṇuvarman in the Golden[END_REF]). Although such coin adaptations are missing from Óc Eo sites, but other denominations assigned to the KT series were found at OE (Borell 2017d: 170, 174) providing more evidence of links between the two sites.

To sum up, the Kra Isthmus sites are ports with early dates and provide Mediterranean imports mostly, glass being the most frequent. While the Mekong Delta sites are mostly later and yielded imports of later dates. The two regions only share a limited number of similarities regarding material types. Those include imported gold glass and mosaic beads and inspired engraved gems with Gandharan connection. However, those latter have different dates in the Kra Isthmus and in the Mekong Delta. More connection can be seen between P. Thailand and the Mekong Delta. Those include gold glass beads, engraved gems of post-second century dates, and particularly coin adaptations of certain types.

Future avenues of research

Comparative studies combining raw materials (provenance), style and techniques, of more materials with secure context would contribute to this objective. This would also help to differentiate the various inspired imports, to identify local variations and a greater number of similar objects from Óc Eo and the TMP, thus providing a more comprehensive understanding of the connections between the two regions.

Discussion

The various comparative studies presented in this article are heterogeneous. Some studies combine physico-chemical studies while others are based solely on morpho-stylistic studies. The majority are limited by the absence of context and therefore of dating. Nevertheless, the comparisons reveal similarities and differences between the TMP and the Mekong Delta over the periods and allow us to make several observations about the links or developments between the two regions. [START_REF] Dussubieux | First elemental analysis of glass from Southern Myanmar: replacing the region in the early Maritime Silk Road[END_REF]). In the TMP, developments in the glass and semi-precious stone industries are linked at least during the late prehistoric period. We have no data on this subject for the early historical period (Khlong Thom). In both regions, there was a shift in the types of production, with simpler morphologies, some specific to the region, and the implementation of mass production techniques. Either the production is larger and reaches a wider audience, or the material has lost its value in favour of other types of production [START_REF] Bellina | Témoignages archéologiques d'échanges entre l'Inde et l'Asie du Sud-Est, morphologie, morphométrie et techniques de fabrication des perles en agate et en cornaline (VIe siècle avant notre ère -VIe siècle de notre ère)[END_REF]. For both industries, physico-chemical studies to determine the origin of the materials and a technological study would be beneficial in three respects. They would make it possible to refine:

-the dating of historical production in TMP based on material in the Óc Eo context.

-regional connections between the two regions.

-our understanding of the differentiated productions that may have been aimed at distinct social groups. These studies would bring insights into the socio-political organization of these polities.

Regarding metals, there are comparable gold ornaments in the Mekong delta and the TMP from the prehistoric period. It is likely that further comparative studies will enable identify other comparable materials made with copper alloys. Those have great potential for shedding light on Óc Eo's regional networks, particularly between the TMP during the late prehistoric and early historic periods. Studies of Mediterranean material show that the two regions share certain trends. Most objects of Mediterranean inspiration have been found in Khlong Thom and Óc Eo. Imports were more numerous in the Isthmus of Kra during the early period. All types of imports and material adapted from glass and semi-precious stones, gold foil beads, mosaic beads and Gandhara-inspired seals are found in both regions. As far as Mediterranean material is concerned, the connections between the two regions are mainly visible for sites from the historic period.

There is evidence of contact in both the late prehistoric and early historic periods, although the former is more numerous due to the state of research. The main limitations of this study are the lack of material in context and of dating, since most of the comparisons were made based on old collections, often collected by villagers. However, the many large-scale excavations carried out by Vietnamese excavation programs in recent years have produced a large amount of data in context allowing for efficient comparisons [START_REF] Bùi | ngoài trong văn hóa Óc Eo: nhận thức mới từ tiếp cận nghiên cứu so sánh (Foreign ceramics in Oc Eo culture: new perception from comparative research approach[END_REF].

Conclusion

Each industry sheds a different light on production and distribution networks, allowing inferences to be drawn about social and economic organisation. The imports and hybrid productions identified for ceramics, semi-precious stones and glass reveal interactions between the two regions. Glass, semiprecious stone, and metals were highly sought after in ancient times. Merchants and craftsmen also moved around and settled in the ports. It is therefore highly likely that the combined study of these materials and the techniques used to produce the different types of products in the Mekong Delta and TMP could shed light not only on regional networks, but also on their social and economic organisation and evolution during the late prehistoric and early historic periods. The political organisation composed of multiple centre could also be better understood, their relations with Oc Eo and Angkor Borei for instance and the relationship between those two. Future research using harmonised analytical methods would also make it possible to assess the nature of the relationships and the extent to which developments in the two regions are linked over time. More generally, comparative studies would contribute to a better understanding of the developments that took place at the beginning of the historical period in the South China Sea, of which the Mekong delta and the TMP visibly linked regions are essential cornerstones.

Figure 1 .

 1 Figure 1. Left, gold foil beads and glass beads with birds from Óc Eo (Malleret 1962) ; Right: beads from Khlong Thom (photos B. Bellina)

figure 2 :

 2 figure 2: semi-precious stone ornaments from Giong Ca Vo, Khao Sam Kaeo, Óc Eo and Khlong Thom. Photos B. Bellina

  : Plate XII), and to numerous similar beads from sites in Burma some said to come from Pyu sites (Richter 2000) others observed in private collections (U Win Muang). Óc Eo yielded gold granulated beads(Malleret 1962, volume 3, pl. XII, bottom right). KSK and Aw Gyi in the Isthmus yielded similar beads such as. Further east, more than 30 polyhedral beads were found in Hepu. Others were found in Han-period tombs in southern China in Ganquan of Jiangshu, Wulipai of Changsha and Guangzhou of Guangdong (Xiong Zhaoming and Lin Ying 2019).

Figure 3 .

 3 Figure 3. Gold ornaments from Khao Sam Kaeo (except top right one from Malleret 1962). Photos B. Bellina.

Figure 3 .

 3 Figure 3. Mediterranean engraved gems from TPM and from OE (1-4: Khlong Thom; 5: Óc Eo; 6: Đá Nổi). After Bouzek & Ondřejová 2009: figs 1-3; Borell et a.l 2014: 104, fig.8a-b; Borell 2016b: 110, fig.8, 111, fig. 13; Figure 4 Inspired engraved gems from TPM and OE (1-2: Phu Khao Thong; 3: Bang Kluai Nok; 4-7: Óc Eo). After Borell 2017b: 62, fig.3; Kangked 2009: 88; Borell et al. 2014: 103, fig.7; Borell 2016b: 110, figs. 9-12.

  As far as ceramics are concerned, there are rare types in TMP that are found in the Mekong Delta during the Óc Eo period. Several imported ceramics and others that we call hybrids in TMP, often produced locally with exogenous techniques and/or styles, may not yet have been spotted in the Mekong Delta. Certain types of ceramics have been found at other sites around Óc Eo. Comparative studies of local and imported ceramics therefore have great potential. The paucity of analyses carried out on glass in the context of Óc Eo and early historical TMP sites is one of the main limiting factors for comparisons between the two regions. Especially as the two major sites, Óc Eo and Khlong Thom have a long occupation sequence. Local glass and semi-precious stone ornament industries seem to have developed in parallel. The networks that supplied Angkor Borei during the last centuries BC and the first centuries AD are to be found in south-east India[START_REF] Carter | Angkor Borei and protohistorical trade networks: a view from the glass and stone bead assemblage[END_REF]. What about the Óc Eo networks? Are they the same? In the TMP, sites dating of the late centuries BC and early centuries AD such as Bang Kluay Nok and Phu Khao Thong show links with Arikamedu in particular, whose glass type is different

  Yamagata, Mariko, Pham Duc Manh, and Bui Chi Hoang. 2001. 'Western Han Bronze Mirrors Recently Discovered in Central Vietnam'. Bulletin of the Indo-Pacific Prehistory Association 21 (The Melaka Papers 5): 99-106. Yamagata, Mariko. 2007. « The early history of Lin-i viewed from archaeology ». Acta Asiatica 92: 1-30. Yamagata, M. 2013. The excavation of Hoa Diem in Central Vietnam. In: Showa Women's University Institute of International Culture Bulletin, vol. 17, Showa Women's University Institute, Tokyo. Xiong Zhaoming and Lin Ying 2019. Chinese Knowledge on Suvarnabhumi before the 10 th century. In The Golden Land Suvarnabhumi. The new finding for Suvarnabhumi Terra Incognita. Bunchar and Somchet Thinapong (eds.), Bangkok: GISTDA, 116-125 Maps&Illustrations Map 1: Sites from the Upper Thai-Malay peninsula mentioned in the text. Map 2: Mediterranean import and inspired engraved gems from TMP and OE Table1: similarities between ceramics from the Thai-Malay Peninsula and Oc Eo (pictures for Thai-Malay Peninsula ceramics: A. Favereau).Table2Mediterranean engraved gems from TPM and from OE (1-4: Khlong Thom; 5: Óc Eo; 6: Đá Nổi). AfterBouzek & Ondřejová 2009: figs 1-3; Borell et a.l 2014: 104, fig.8a-b; Borell 2016b: 110, fig.8, 111, fig. 13; Table3Inspired engraved gems from TPM and OE (1-2: Phu Khao Thong; 3: Bang Kluai Nok; 4-7: Óc Eo).After Borell 2017b: 62, fig.3; Kangked 2009: 88; Borell et al. 2014: 103, fig.7; Borell 2016b: 110, figs. 9-12.