Katia Chirkova

Skalbzang Tshering

Verb Stem Alternations in Pingwu Baima

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Introduction

This paper focuses on verb stem alternations in the Pingwu variety of Baima (ISO-639 bqh), a little-studied Tibetic (Tibeto-Burman) language spoken at the border of Sichuan 四川 and Gansu 甘肃 provinces in the People's Republic of China. Baima has approximately 10,000 speakers, who reside in the counties of Pingwu 平武, Songpan 松潘 / Zung chu, Jiuzhaigou 九 寨沟 / Gzi rtsa sde dgu in Sichuan Province and in the counties of Wenxian 文县 and Zhouqu 舟曲/ 'Brug chu in Gansu Province (see H. Sun et al. 2007: 1;Suzuki 2015: 120). The area of the distribution of the Baima language lies at the historical Sino-Tibetan border, which is home to diverse varieties of Tibetic, 1 Qiang (or Rma), 2 Chinese (Mandarin), and Rgyalrong languages. 3 Map 1 shows the area of the distribution of Baima and some of its neighboring languages. (Transcriptions for language names follow conventions in their respective descriptions. Tibetan county names are in Wylie's 1959 transcription.) Map 1. Distribution of Baima and some of the neighboring languages Most previous work on Baima has centered on only one variety (that of Pingwu county) with a focus on the disputed status of Baima as either a dialect of Tibetan (or a member of the Tibetic language family) (see Awang Cuocheng & Wang 1988;Zhang 1994aZhang -b, 1997;;[START_REF] Bufan | Baima zhishu wenti yanjiu 白马话支 属问题研究 [A study of the genetic affiliation of Baima[END_REF] or an independent Tibeto-Burman language (see H. Sun 1980aSun -b, 2003;;Nishida & H. Sun 1990;H. Sun et al. 2007). Verb stem alternation in Pingwu Baima (hereafter Baima) has been made part of the argument in some more in-depth descriptions. These include, on the one hand, Huang & [START_REF] Bufan | Baima zhishu wenti yanjiu 白马话支 属问题研究 [A study of the genetic affiliation of Baima[END_REF] and, on the other hand, Nishida & H. [START_REF] Tatsuo | Hakuba yakugo no kenkyū: Hakuba no kōzō to keitō 《白馬譯語の研究: 白馬語の構造と系统》 [A study of the Baima-Chinese vocabulary 'Baima yiyu': the structure and affiliation of the Baima language[END_REF] and H. Sun et al. (2007). Of the latter two studies, H. Sun et al. (2007) is an updated and expanded version of the analysis in Nishida & H. Sun (1990: 230-232). For that reason, H. Sun et al. (2007) is used hereafter as a collective reference to both studies.

Huang & [START_REF] Bufan | Baima zhishu wenti yanjiu 白马话支 属问题研究 [A study of the genetic affiliation of Baima[END_REF] and H. Sun et al. (2007) agree in describing verbs in Baima as having up to three different stems associated with TAM categories, specifically:

(1) one stem that bears a non-past function and may denote prospective, factual, habitual, and present progressive meanings (hereafter non-past);

(2) one stem that has past-time reference and is predominantly used in the perfective, terminative, and past imperfective (hereafter past);

(3) an imperative stem. 4At the same time, Huang & Zhang (1997) and H. Sun et al. (2007) differ in their presentation of some basic facts (such as the frequency of alternating verbs in Baima) and in their methodological approaches (involving or not comparison with etymologically related WT forms). Remarkably, this results in diametrically opposed interpretations of data from one and the same variety of Baima.

Huang & Zhang (1995: 107) report that only a few Baima verbs are alternating in their data (a list of 2,343 words). They examine alternating verbs in relation to their Tibetan etymologies to conclude that verb paradigms in Baima are similar to those known from Written Tibetan (hereafter WT). Zhang (1995: 107) Huang & [START_REF] Bufan | Baima zhishu wenti yanjiu 白马话支 属问题研究 [A study of the genetic affiliation of Baima[END_REF] report only two verbs with three stems in their data ('go' and 'eat'). In verbs with two stems (e.g. 'dig', 'look', 'sell'), the past stem is said to commonly combine the functions of the past and imperative stems in the corresponding WT paradigm. However, other configurations also appear possible, as in 'sit, stay', where one stem is said to combine the functions of the present, future, and past stems in the corresponding WT paradigm, while the other stem is imperative. Based on examples of alternating verbs in their data, Huang & Zhang suggest that the development of the WT patterns of stem formation in Baima is most close to that in Kham Tibetan dialects (ibid., p. 115).

H. Sun et al. (2007: 80-84, 199-201) report a higher frequency of alternating verbs in their data (a list of ca. 3,000 words). In their estimation, approximately one third of randomly selected 100 verbs are alternating. Their analysis distinguishes two types of stem alternation, which they discuss separately, namely: (1) aspectual (with one stem used in the prospective and progressive aspect and the other stem used in the perfect and perfective aspect), and ( 2) mood (with one base stem and one imperative stem). Table 2 reproduces the original examples in H. Sun et al. (2007: 81-83). uɛ³⁵ ʃuɛ⁵³

Table 2. Alternating verbs in H. Sun et al. (2007: 81-83) H. Sun et al. restrict their analysis to synchronic data to conclude that (i) both types of stem alternation are unpredictable (H. Sun et al. 2007: 82-84) and (ii) their underlying morphology is distinct from that in Tibetic languages. The main argument is that imperative verb stem formation in Baima may be variously expressed through (1) onset alternation (as in 'wash (clothes)', 'burn (firewood)' in Table 2), (2) vowel alternation (as in 'weep', 'look'), or (3) a combination of onset and vowel alternation (as in 'patch (a garment)'); whereas in Tibetic 6 This verb etymologically reflects the WT verb 'do; make' (see Table B.1 in the appendix).

7 One of the anonymous reviewers suggests that the suppletion pattern in the verb 'come' alone may be enough to prove that Baima is a Tibetic language. That suppletion pattern in Tibetic languages (WT 'ongs -shog) is similar to the suppletive pattern in the adjective 'good' in Germanic languages (e.g. Fulk 2018: 220-221), which is often cited in textbooks on historical linguistics as a way to prove that a language is Germanic (e.g. Hock 1991: 563-564). We note, however, that Baima /uɛ / does not regularly correspond to WT 'ongs (see verb 6 in Table B.1) and, moreover, the etymology of that Baima form is uncertain. For that reason, we prefer to err on the side of caution and do not consider that specific suppletion pattern as diagnostic evidence to prove that Baima is a Tibetic language.

languages, the main form of imperative stem formation is o ablaut (H. Sun et al. 2007: 199-200).

As can be glimpsed from the summaries above, with their limited number of mostly non-overlapping examples, differences in methodological approaches, and contradictory findings, the previous in-depth descriptions of Pingwu Baima provide an at-best incomplete picture of stem alternation in that variety. Differences in methodological approaches also inevitably affect some of the conclusions. Most importantly, that H. rather than with the imperative stem, viz., khrus. That being the case, the observed difference between imperative forms in Baima and Tibetic languages is likely not the result of differences in the underlying morphology of imperative stem formation, but rather follows from the elimination in many Baima alternating verbs of separate imperative stems of classical paradigms.

The present study takes a new look at verb stem alternation in Pingwu Baima by examining a larger corpus of data than the corpora in previous works, and by consistently applying to the corpus one uniform methodological approach-systematically relating alternating verbs to corresponding classical WT paradigms. Our goals are:

(1) to systematically elicit all possible verb stems of high frequency Baima verbs in order to independently assess the relative frequency of alternating verbs in this language;

(2) on that basis, to get a better understanding of the development of the classical patterns of stem formation in Baima.

Our data reveal a relatively high number of alternating verbs in Baima. A systematic comparison of alternating verbs to corresponding classical paradigms confirms that stem alternations in Baima regularly reflect both affixal and ablaut Old Tibetan (hereafter OT) verb morphology. 8 Such a comparison also confirms a clear tendency toward elimination in Baima of a separate imperative stem of classical paradigms, as can already be glimpsed from Huang & [START_REF] Bufan | Baima zhishu wenti yanjiu 白马话支 属问题研究 [A study of the genetic affiliation of Baima[END_REF] and H. Sun et al. (2007) data. Such a tendency has not been commonly reported in modern Tibetic languages. An examination of Baima verb stem alternation in the context of its neighboring Tibetic and non-Tibetic varieties, such as Rgyalrong, where verb-stem differentiation is a highly visible feature (J. Sun 2014b: 633), suggests language contact as a possible trigger for this development.

The remainder of the paper is organized as follows. Section 2 provides information on the data and methodology of this study. Section 3 analyses alternating verbs in relation to their corresponding WT paradigms. Section 4 discusses the development of verb alternation in Baima in the context of the neighboring languages. Section 5 sums up the major findings and rounds off the paper. Appendix A provides an overview of synchronic and historical phonology of Baima. Appendix B provides a complete list of verbs in our study.

Data and methodology

For this study we have selected 250 verbs from the list of the Tibeto-Burman core vocabulary in [START_REF] Dai Qingxia | Zang-Mian Yuzu Yuyan Cihui 《藏缅语族语言词汇》 [A Tibeto-Burman lexicon[END_REF]. The verbs on the list were first recorded in isolation (in citation form) and then as placed in a set of contexts representing major TAM distinctions, modeled on [START_REF] Dahl | Tense and Aspect Systems[END_REF] TAM questionnaire, and also including an explicit imperative context. 9 The data were recorded in July 2019 with one male speaker, Mr. Li Degui 李德贵, the main language consultant of the first author. 10 The elicited verbs include 15 (non-alternating) loan verbs from 8 Old Tibetan refers to the phonological system underlying traditional Tibetan orthography, which for the most part can be recovered through a comparison of the modern dialectal reflexes of the orthographic (Written Tibetan) forms. This and other stories in the corpus do not contain examples of the use of that verb in the imperative. Overall, of the 39 verbs that occur in that story, only two verbs occur in the imperative: 'come' (/ʃuɛ̂/) and 'put, place' (/ʒɑ̂/).

Onset and/or vowel alternation is hence the dominant strategy in verbs with two stems, while suppletion is the dominant stem derivation strategy in verbs with three stems. The citation stem in verbs with three stems is the imperative stem (e.g. /dzʊ ̀/ for the verb 'speak; say', see verb 5 in Table B.1), and it is the past/imperative stem in verbs with two stems (e.g. /tsŷ/ for the verb 'prick, thrust', see verb 29 in Table B.2).

All stems of alternating verbs in our data were supplied with Tibetan etymologies. Given that our list of common verbs overlaps with the list of verbs in Nishida & H. [START_REF] Tatsuo | Hakuba yakugo no kenkyū: Hakuba no kōzō to keitō 《白馬譯語の研究: 白馬語の構造と系统》 [A study of the Baima-Chinese vocabulary 'Baima yiyu': the structure and affiliation of the Baima language[END_REF], it was possible in the majority of cases to rely on the Tibetan etymologies proposed by Zhang Jichuan (1994a-b) for that latter word list. Note that the word list in Nishida & H. Sun does not systematically provide different stems of alternating verbs and indicates in most cases only one (citation) stem of a given alternating verb. Accordingly, Zhang (1994a-b) only provides Tibetan etymologies for the listed (citation) forms. Table 4 gives examples of alternating verbs, as elicited in our data, compared to the forms of those verbs in Nishida & H. [START_REF] Tatsuo | Hakuba yakugo no kenkyū: Hakuba no kōzō to keitō 《白馬譯語の研究: 白馬語の構造と系统》 [A study of the Baima-Chinese vocabulary 'Baima yiyu': the structure and affiliation of the Baima language[END_REF], and accompanied by the Tibetan etymologies in Zhang (1994a-b). (1994a-b) All Tibetan etymologies were double-checked by the second author, a native Tibetan linguist.

In a few cases, new or missing etymologies were provided (e.g. 'bark (dog)', 'be drunk', see below).

As the next step, the Tibetan etymologies from Zhang (1994a-b) were supplied each with a complete list of all attested stems of that verb, as reported in Tibetan dictionaries. The 5. A comparison of the alternating verbs in our data with the corresponding WT paradigms suggests that in the vast majority of cases, Baima alternating verbs can be related to the attested stems of WT verbs through regular sound correspondences between Baima and WT (see Appendix A). Furthermore, such a comparison reveals the following tendencies in the simplification of the originally complex OT verb paradigms in Baima.

First, as already noted in Huang & [START_REF] Bufan | Baima zhishu wenti yanjiu 白马话支 属问题研究 [A study of the genetic affiliation of Baima[END_REF], Baima reduces the opposition between the present and the future stems of classical paradigms to a single stem. This is a common development in modern Tibetic languages, where the non-past or imperfective stem generally corresponds with the present stem of Written Tibetan (cf. suggesting an underlying form that is not attested.

In 45 verbs (or 74%) out of the total of 61 alternating verbs in our corpus, all stems can be related to the attested stems of corresponding classical paradigms through regular sound correspondences between Baima and WT. In 13 verbs (or 21% of all alternating verbs), one of the stems shows irregular sound correspondences with the attested stems (onset, rhyme or tone), thereby suggesting an underlying form that is at variance with the attested forms. 5, the would-be source of the non-past stem is *'bya, whereas the would-be source of the past/imperative stem is *phya, both unattested forms for this verb in WT. Appendix B provides complete lists of verbs in our corpus together with their suggested etymologies. The following section discusses the morphology of verb stem alternation in Baima.

Morphology of verb alternation in Baima

In contrast to the conclusions in H. Sun et al. (2007), our data suggest that the underlying morphology of verb stem alternation in Baima is distinctly that of Old Tibetan.

Recall that classical WT verb paradigms consist of four stems at the most, traditionally labeled present, past, future, and imperative. The four verb stems show a variety of prefixes, suffixes, and ablaut, with sound changes obscuring in some cases the system (see [START_REF] Coblin | Notes on Tibetan verbal morphology[END_REF][START_REF] Beyer | The Classical Tibetan Language[END_REF][START_REF] Hill | A Lexicon of Tibetan Verb Stems as Reported by the Grammatical Tradition[END_REF][START_REF] Hill | Sino-Tibetan: Part 2, Tibetan[END_REF]Hill , 2019: 9-21, 42-44: 9-21, 42-44). An overview of Tibetan verb morphology in Hill (2010: xv-xxi) classifies WT alternating verbs into 12 paradigms, as reproduced in Table 6. (WT dras), to compare, the non-past stem of that verb is / n dʐa̠ ̂/ (WT dra). However, when added 13 The prefixes g-and b-disappeared irrespective of voicing of the root initial. Before being elided, they acted as a buffer against devoicing of the following root initials, yielding modern voiced obstruents and sonorants. On the other hand, in clusters with the root initial l-, the preinitials g-and b-have likely been lost early in the history of Baima, as their reflexes are the same as that of a simplex l-(that is, Baima j-). Examples include WT lag pa 'hand', gla ba 'musk deer', yielding both Baima /jɑ̄/; WT (yar) lang 'get up', blangs, the past stem of the verb 'take, hold', yielding both Baima /jō/.

paradigm present past future imperative 1 '-_ _-s 2 '-_ 3 '-_-d b-_ 4 _-d b-_-s 5 g-_ _-s 6 b-_ 7 '-_-d d-_ 8 b-_-s 9 '-_ bX-_-s b-_ 10 X-_-s 11 '-_-d bX-_ d-_ 12 bX-_-s
to closed rhymes, the suffix -s is generally lost without compensation, as in 'pick, pluck': the non-past stem /ⁿd ʢ uɛ̂/ (WT 'thog); to compare, the past/imperative stem of that verb is /tuɛ̂/ (WT btogs). 14 Finally, our Baima data provides no consistent evidence for da-drag or a postfinal -d that could follow the codas -n, -r, -l before the standardization of the Tibetan script in the 9th century (e.g. Beyer 1992: 169, 175;[START_REF] Zhang | The puzzle of da-drag in Tibetan[END_REF]). The tone of Baima words which historically ended in -d are for the most part the same as in words which historically did not end in -d. For example, the Baima reflex of the past stem of the verb 'sleep', viz., nyald, is homophonous with the reflex of nyal 'fish', both /ɲɛ̄/. 15 The regular developments above lead to the development of three distinct patterns of stem formation in verbs with two stems, as already identified in H. Sun et al. (2007) (see Table 2) and as also observed in our data (see Table 3). ( 1 The marginal productivity of the vowel alternation pattern of stem formation is likely observed in the case of the verb 'ache; be painful' (see verb 11 in Table B.3). This verb is alternating in Baima (its non-past stem is /tsʰa̠ ̂/, and its past stem is /tsʰê/), whereas the 17 We are grateful to the anonymous reviewer for this suggestion.

(V)1 CV(V)1 CV(V)2 2-3 '-_(-d) b-_C-s 7-8 '-_-d b-_C(s) 9 '-_ bX-_C-s 10-12 '-_(-d) bX-_C(-s) 4 _-d b-_-s 5 g-_ b-_-s C1V(V)1 C1V(V)2 6 g-_ b-_
corresponding WT verb is non-alternating (tsha). It can be tentatively proposed that the past stem of this verb is derived from the non-past stem through innovative ablaut (a > e).

Finally, the reasons for the irregular relationship between both stems of the Baima verbs 'open (door)' (verb 22 in Table B.2), 'sweep' (verb 15 in Table B.2), and 'close, shut (door)'

(verb 13 in Table B.3) and the attested stems of classical paradigms are more obscure. These Baima verbs cannot be identified with any known Tibetan roots and may have yet unidentified sources.

Baima verb stem alternation in the context of the neighboring non-Tibetic varieties

As discussed in the previous section, the patterns of stem formation in Baima unmistakably reflect OT verb morphology. At the same time, they evidence one relatively uncommon tendency in the development of the originally complex OT patterns: that of elimination of a separate imperative stem of classical WT paradigms, whereby the past stem comes to serve both past and imperative functions. Such a tendency has not been commonly reported for modern Tibetic languages and it likely represents an innovative development. We further note that that development may not be limited to Baima, but may be shared with its neighboring Tibetic varieties (see Map 1). A preliminary comparison is possible with Zhongu (a Tibetic variety of Songpan county), for which an extensive vocabulary list of 1,500 common lexical items with their suggested Tibetan etymologies is available (see J. [START_REF] Hongkai | Is Baima a dialect or vernacular of Tibetan?[END_REF]. That list yields a total of 35 verbs that overlap with verbs on our Baima list. The majority of those overlapping verbs (20 in total) have two stems that distinguish, similar to Baima, between one non-past stem, which corresponds with the present stem of classical paradigms, and one stem serving both past and imperative functions, which corresponds with the past stem of classical paradigms. Among the remaining 15 verbs, 6 verbs have three stems in both Zhongu and Baima, including a separate imperative stem (see verbs in Table B.1), while 9 verbs have two stems in Baima and one or three stems in Zhongu. The relatively uncommon tendency in Baima and possibly its neighboring Tibetic varieties to eliminate a separate imperative stem of classical paradigms can be further considered in the context of local non-Tibetic languages, some of which, most importantly

Rgyalrong, also have complex patterns of stem alternation.

Rgyalrong verbs have a maximum of three stems, conventionally labeled 1, 2, 3, following J. Sun (2004Sun ( , 2014b)). Stem 1 occurs in non-past contexts; stem 2 occurs in past contexts; stem 3 occurs only in some highly specific transitive contexts constrained by number (singular), tense-aspect (non-past, non-progressive), and direction (direct) (e.g. J. Sun 2014bSun : 633-634, 2016;;[START_REF] Jacques | Rgyalrong Language[END_REF]Jacques , 2021: 493-499): 493-499). Most Rgyalrong varieties are reported to have only two stems (stem 1 and stem 2), commonly differentiated through (partially productive) ablaut. Put differently, unlike Tibetic languages, Rgyalrong verbs lack a separate imperative stem and commonly distinguish between one stem used in non-past contexts and one stem used in past contexts. In this context, the tendency to eliminate a separate imperative stem in Baima and its neighboring Tibetic varieties can potentially be interpreted as a type of remodeling of the originally complex OT paradigms to better reflect the stem differentiation in the nearby non-Tibetic (Rgyalrong) languages.

At the same time we note that while such an interpretation is conceivable, it stands in contrast with some reported cases of language contact between Tibetic and Rgyalrong languages in the area. Gserpa and Khalong (see Map 1), two Tibetic varieties in close contact with Showu Rgyalrong (J. Sun 2006Sun : 114-116, 2007Sun , 2016[START_REF] Evans | Qiāng 羌 language[END_REF], are a case in point. Both 19 One of the anonymous reviewers notes that, although the levelling of verb stem alternations in favor of the etymological past has not often been discussed in the literature, it is by no means rare in Tibetic languages. The reviewer cites Lhasa Tibetan as an example, noting that the most recent sources on that variety, in particular the Bod rgya tshig mdzod chen mo [The Great Tibetan-Chinese Dictionary] (1993), offer numerous examples of the levelling of the inflection of some originally complex paradigms in favor of the etymological past. We note that while such a tendency may not be uncommon, no other reported variety shows it to such an extreme extent as

Summary and conclusion

In this study we presented a new analysis of verb stem alternation in the Pingwu variety of Baima, based on a small corpus of 250 common verbs. The main findings include:

(1) Baima has a relatively high number of alternating verbs and complex verbal morphology in the sense of stem alternation (affixal, ablaut). In contrast to the conclusion in Huang & Zhang (1995: 115), this is quite unlike Kham Tibetan varieties and more in line with Amdo varieties.

In fact, Baima shares several diagnostic developments with its neighboring Amdo varieties, including the semantic extension of 'chew, gnaw' to 'eat' (see section 3).

(2) In contrast to the conclusions in H. Sun et al. (2007), the morphology of stem alternation in Baima is clearly that of OT, consistently reflecting both regular and irregular OT morphology.

Observed irregularities may be largely ascribed to analogical changes.

(3) One potentially innovative development in Baima is a tendency to eliminate a separate imperative stem of classical WT paradigms. That development is likely shared by Baima with its neighboring Tibetic varieties, such as Zhongu. That development may be tentatively attributed to language contact with local non-Tibetic languages. However, the identity of those languages and related mechanisms of borrowing require further investigation, as they appear to be distinct from those in more transparent cases of language contact between local Tibetic and Rgyalrong varieties (Gserpa, Khalong).

Naturally, further work and additional data from more speakers are required to test the robustness of the present conclusions. There is also a need for a comparative study of various Baima varieties (including also those spoken in Songpan, Jiuzhaigou, Wenxian, and Zhouqu counties) so as to allow for a more comprehensive understanding of the evolution of classical patterns of stem formation in this language. Such a comprehensive study has the potential to further our understanding of less common developments in Pingwu Baima. An added bonus is that such a study may shed further light on the dynamics of language contact in small indigenous communities of the historical Sino-Tibetan border areas, which has indubitably played a significant role in the formation of local Tibetic and non-Tibetic varieties alike.

Baima. For that reason, in this particular case we propose to provisionally keep language contact as a possible explanation for the observed developments until more compelling, internal explanations have been found.

a by-product of historically breathy voice, followed by tense voice (laryngealized or creaky phonation of the vowel) (see below). The three contrastive tonal categories in Baima likely arose through an overlay of the phonation difference in consonants (historically breathy vs. plain) and the phonation difference in vowels (tense vs. lax). Syllables with tense vowels acquired a high falling, short tone, the relative pitch height of which is predictable on the phonation type of the syllable onset-higher on syllables with non-epiglottalized onsets, and lower on syllables with epiglottalized onsets, and therefore non-contrastive. Syllables with non-tense vowels, on the other hand, acquired a lower, long tone. That lower long tone subsequently split into two contrastive tones, depending on the historical onset type. Syllables with plain onsets yielded a long level tone with modal voice quality (mid tone), whereas syllables with historically breathy and voiceless aspirated onsets yielded a long low falling-rising tone with breathy-like voice quality (low tone) (see Chirkova under review for detailed discussion). As a result of these complex developments, depending on the historical onset type, Baima reflexes of OT rhymes may vary from voice quality (tense vs. modal vs. lax) to mixed voice and vowel quality contrasts (in particular for long vowels from OT coalesced syllables and rhymes with the codas -n, -ng, -m, -l, -s). Table A.4 summarizes common reflexes of OT rhymes.

A slash ("/") separates reflexes after historically plain initials from those after historically breathy initials, in that order. Baima verbs are listed next to their suggested etymologies (attested WT stems).

Ø (or -r) -b(s) -d -g(s) -n -ng(s) -m(s) -l -s a

Uncertain origins are indicated by question marks in the corresponding syllable slot. Question marks beside suggested etymons signal that the etyma in question are tentative. Baima forms that are at variance with the attested stems are highlighted in gray. Corresponding WT slots of such forms include the closest matching form among the attested stems, followed by the wouldbe source of the irregular Baima form, as proposed on the basis of major sound correspondences between Baima and WT. In the tables, verbs are sorted in the order of the Tibetan consonants followed by the order of the vowels.

No. Gloss Baima WT We tentatively propose that this verb may be etymologically related to the WT verb 'block, obstruct'. That is based on the observation that in a number of Kham dialects (such as the Chaya 察雅 / brag gyab variety of chab mdo Tibetan or the Zhongxinrong 中心绒 / gtsang chen rong variety of 'ba' thang Tibetan), a combination of the verb 'block, obstruct' with the noun khyi 'dog' stands for both 'hold back a dog' and 'dog barks' and is used as an equivalent to the standard expression (khyi) zug 'bark (dog)'. We tentatively suggest that a similar semantic development may have taken place in Baima. 22 We tentatively propose that this verb is etymologically related to the verb 'pher or 'phel with the meaning 'raise', 'increase'. 23 The verb 'be drunk' is listed in Nishida & H. Sun (1990: 356) as /tʃʰo⁵³ pʰɛ¹³ nbɔ¹³ ʃɿ¹³/, where /tʃʰo⁵³/ is 'beer' (WT chang) and /nbɔ¹³ ʃɿ¹³/ are verbal enclitics (completive and non-egophoric) (see [START_REF] Chirkova | Evidentials in Pingwu Baima[END_REF]. No etymology for the verb /pʰɛ¹³/ is provided in Zhang (1994a-b). We tentatively propose that this Baima verb may be related to the form ban, as found in some Tibetan dialects. For example, in 'ba' thang Tibetan, ban is used both transitively and intransitively (respectively, 'moisten' and 'be moist'), and its intransitive use is often extended to stand for 'be drunk'. WT does not have the form ban in the meaning 'be moist' or 'moisten', while it is possible that this form is related to the WT verb b(r)an 'saturate with water, moisten' (with the inflectional paradigm 'bran, bran (d), bran, bran(d)/bron, e.g. Hill 2010: 196).

  consulted sources include Skal bzang ye shes et al. (1958), Mkhyen rab 'od gsal (1976), Dpal khang lo tsa ba et al. (1991), Hill (2010), Pad ma dbang grags et al. (2015), and Bielmeier et al. (2018). The attested stems were listed next to the alternating verbs, as elicited in our data, for comparison. Consider examples in Table

  Gserpa and Khalong have been argued to evidence a Showu Rgyalrong substratum that manifests itself in numerous lexical loans and, most importantly in the context of the present discussion, also verbal morphology. Non-past (or imperfective) stems of alternating verbs in these varieties mostly trace back to WT perfective stems, whereas new past (or perfective) stems have been argued to be created from innovative imperfective stems by means of ablaut, which has clear similarities in form and function with the stem-building ablaut in Showu Rgyalrong. Remarkably, while borrowing morphologically-based phonological alternation from the neighboring Rgyalrong variety, both Gserpa and Khalong appear to retain Tibeticstyle verbal paradigms with a distinct imperative stem, which is many cases reflect the imperative stem of the corresponding WT paradigm. Consider the following examples. The imperfective stem of the verb 'laugh' in both Gserpa and Khalong corresponds with the perfective stem of the classical paradigm, viz., bgad (Gserpa /vga/, Khalong /vgat/). The perfective stem of this verb, on the other hand, is innovated from the imperfective stem via the Rgyalrong-style ablaut (viz., Gserpa /vge/, Khalong /vget/). Finally, the imperative stem corresponds with the WT imperative stem dgod (Gserpa /rgot/, Khalong /rgot/). Unlike Gserpa and Khalong, both Baima and Zhongu contain very few recognizable loanwords from local non-Tibetic languages (e.g.Huang & Zhang 1995: 116-117;[START_REF] Chirkova | On the Position of Báimǎ within Tibetan: A Look from Basic Vocabulary[END_REF] J. Sun 2003: 782-783). Yet they evidence an innovative strategy of verb-stem differentiation which is at variance with commonly observed developments of classical Tibetan patterns in Tibetic languages. More detailed work on local Tibetic and non-Tibetic varieties in the historical multilingual Sino-Tibetan borderlands is clearly needed to shed light on the precise developments in the Baima case.19

  Table A.1. Major trends in the development of Baima consonants. T = voiceless unaspirated obstruent, Tʰ = voiceless aspirated obstruent, D = voiced obstruent, ⁿD = prenasalized stop or affricate, S = plain sonorant. The original complex OT rhyme structure has been drastically simplified in Baima. All original consonantal codas were lost, transforming all closed syllables into open syllables. The disappearance of consonantal codas led to the development of the phonation difference in vowels: tense vs. non-tense or lax, with vowel duration and pitch as co-articulated cues. Tense vowels (with shorter duration and higher pitch) evolved from OT open syllables and syllables with codas -b,-d, -g, 20 whereas lax vowels (with longer duration and lower pitch) evolved from OT coalesced syllables and syllables with codas -m, -n, -ng, -s, -l.

Table 1 .

 1 Table 1 reproduces the original examples in Huang & Zhang (1995: 107) together with their suggested etymologies. Alternating verbs in Huang &

	Gloss		non-past	past	imperative
		Baima WT	Baima WT	Baima	WT
	go	ndʑi⁵³	mchi	tɕʰae³⁵	chas	ndʑuɐ⁵³	'gro
	eat	ndʒa⁵³ 'cha'	ndʒø³⁵	'chos	ndʒuɐ⁵³	'cho~'chos
	rob, plunder ndʐuɐ⁵³ 'phrog	tʂʰuɐ⁵³		phrogs
	dig	ko⁵³	rko, brko	kø³⁵		brkos, rkos
	chase	nde⁵³	'ded	te⁵³		ded
	look	ta⁵³	lta, blta	tø³⁵		bltas, ltos
	sell	ndzu³⁵ 'tshong, btsong	tsʊ³⁵		btsongs, tshong
	make	ndʑu⁵³ 'grub	tʂu⁵³		grub
	sit; stay	dy⁵³	sdod, bsdad, bsdad		de³⁵ [sic.] 5	sdod

  Sun et al. do not link Baima verbs to etymologically related WT forms obscures the fact that in verbs with two stems (that is, all verbs in Table 2 but 'eat', 'go', and 'come'), one single stem serves both past (perfect/perfective) and imperative functions and regularly corresponds with the past stem of

classical WT paradigms. This can be illustrated with the verb 'wash (clothes)'. The past (perfect/perfective) and imperative stems of that verb are manifestly identical, /tɕy⁵³/. Based on regular correspondences between Baima and WT (as in Zhang 1994a-b), the form /tɕy⁵³/ regularly corresponds with the past stem of the classical paradigm for 'wash', that is, bkrus,

Stem alternation strategy No. of stems No. of verbs

	Chinese and 6 periphrastic constructions consisting of a native Baima word followed by the
	(alternating) auxiliary verb 'do; make' (see Table B.6 in Appendix B). Among the remaining
	229 native Baima verbs, 168 (or 73% of all native Baima verbs) are non-alternating (that is,
	with only one stem), while 61 verbs (or 27% of all native Baima verbs) are alternating. Among
	the alternating verbs, 6 verbs have three stems (non-past, past, imperative), and 55 verbs have
	two stems (non-past and past/imperative). In contrast to Huang & Zhang (1995) and more in
	line with H. Sun et al. (2007), our data hence show a relatively high number of alternating verbs
	(representing over a quarter of all native Baima verbs). Verbs with two stems, of which one
	bears a non-past function and the other stem serves both past and imperative functions,
	constitute the absolute majority (90%) of all alternating verbs. Observed stem alternation
	strategies include, on the one hand, onset and/or vowel alternation and, on the other hand, more
	marginally, suppletion. Table 3 details the distribution of these strategies in our verb list.
	onset and/or vowel alternation onset alternation	two	29
	onset and vowel alternation two	6
	vowel alternation	three	2
		two	19
	suppletion	three	4
		two	1
	Total		61
	9 Sample contexts include the following:
	(13) [A: When you visited your brother yesterday, what he DO after you had dinner? ANSWER:] He WRITE
	letters.
	(16) [Q: What your brother DO when we arrive, do you think? (= What activity will he be engaged in?)] He
	WRITE letters.
	(18) What you brother usually DO after breakfast? A:] He WRITE letters.
	(22) [Q: What are you planning to do right now? A:] I WRITE letters.
	(25) [A: My brother works at an office. B: What kind of work he DO?] He WRITE letters.
	(137) When I COME home (yesterday), he WRITE two letters (=he finished writing them just before I came).
	Imperative: WRITE letters!
	10 The resulting paradigms were cross-checked for consistency with different verb stems as they occur in a corpus
	of traditional stories recorded with four elderly Baima speakers between 2003 and 2017. (That corpus is in part
	available in the Pangloss Collection, see https://pangloss.cnrs.fr/corpus/Baima?lang=en). Our main reason to rely
	on elicitation rather than on the analysis of the verb stems as they occur in that corpus is that traditional narratives
	tend to rely more heavily on the use of past stems, so that instances of non-past and, in particular, imperative stems
	are infrequent. As a result, narratives rarely contain complete verbal paradigms. Hence, due to the lack of
	appropriate contexts, for individual verbs it is often impossible to establish whether they are alternating or not.
	These points can be illustrated with the verb 'herd' in the story "An orphan and a fox" (see Chirkova 2005; H. Sun

Table 3 .

 3 Stem alternation strategies in the verb list in our study

	et al. 2007: 365-374; the sound file is available at https://pangloss.cnrs.fr/corpus/Baima?lang=en). Of the six
	occurrences of the verb 'herd' in that story, three make use of the present stem (/ⁿdzɞ̂/), as in the following example:
	(Abbreviations used in interlinear glossing follow the Leipzig Glossing Rules (LGR,
	http://www.eva.mpg.de/lingua/resources/glossing-rules.php). Non-standard abbreviations include: EGO =
	egophoric.)
	ɲə̂=rɛ̂	tsɑ̄	rɐ̂-ŷ	ⁿdzɞ̂-ɲə̂		ɕɛ̄	ʃə
	person=COM vicinity goat-sheep herd.IPFV-person	do.PFV PFV.N-EGO
	'[The orphan girl] served as a herding girl to other people.'
	The remaining three occurrences make use of the past stem (/ⁿdzʊ ̀/), as in the following example:
	ɲə̂-rɛ̂	tsɑ̄	rɐ̂-ŷ	ⁿdzʊ ̀	ʃə
	person=COM vicinity goat-sheep herd.PFV/IMP PFV.N-EGO
	'[She] herded goats and sheep for other people.'

Table 4 .

 4 Examples of alternating verbs, as elicited in our study, compared to the forms in

	Gloss	Elicited		Nishida & H. Sun	Zhang (1994b)
		N-PST	PST	IMP	(1990)
	speak; say	dzɞ̂	dzɛ ̀	dzʊ ̀	dzø³⁵	zlos
	prick, thrust	ⁿdzŷ	tsŷ		tsu⁵³	btsugs
	split open	ŋ ɡa̠ ̂	kē		ke³⁵	bkas
	open (door)	ⁿdʑa̠ ̂	ɕʰa̠ ̂	ɕʰa⁵³	phye

Nishida & H.

[START_REF] Tatsuo | Hakuba yakugo no kenkyū: Hakuba no kōzō to keitō 《白馬譯語の研究: 白馬語の構造と系统》 [A study of the Baima-Chinese vocabulary 'Baima yiyu': the structure and affiliation of the Baima language[END_REF]

, and accompanied by Tibetan etymologies suggested in Zhang

Table 5 .

 5 Baima alternating verbs next to the attested stems of the corresponding WT verbs.Tibetan etymologies for Baima forms are highlighted in bold. Baima forms that show irregular sound correspondences with the attested stems are highlighted in gray.

  Only 8 verbs in our corpus appear to retain a separate imperative stem of WT paradigms. Of these, 6 verbs have three stems, that is, including a distinct imperative stem that corresponds with the imperative stem of the classical paradigm. For example, the imperative stem /dzʊ ̀/ of the verb 'speak; say' in Table5regularly corresponds with the imperative stem zlos of that verb in WT. The remaining 2 verbs, namely 'look' and 'drink', have two stems. The past/imperative stem of the verb 'look' exceptionally corresponds with the imperative stem of the corresponding WT paradigm (Baima /tyʉ̄/, WT ltos), rather than with the past stem (that is, WT bltas), as in most verbs with two stems.12 The imperative stem of the verb 'drink' (/ⁿdù/) is identical with the present stem (also /ⁿdù/) due to regular sound change (the two stems are distinct in WT, respectively, 'thungs and 'thung). The past stem of the verb

Zeisler 2004: 876-888)

.

11

In our corpus, the non-past stem of Baima alternating verbs regularly corresponds with the present stem of classical paradigms. Examples include: 'speak; say': Baima /dzɞ̂/, WT zlo; 'prick, thrust': Baima /ⁿdzŷ/, WT 'dzugs or 'dzug (note that in Baima, the developments in consonantal clusters in the coda position, i.e. -Cs, are identical to those of a simple consonantal coda, see

Table A.4 in Appendix A).

Second, alternating verbs in Baima attest to a consistent elimination of a separate imperative stem of classical paradigms. In the vast majority of alternating verbs with two stems (that is, 53), the originally distinct functions of the past and imperative stems are expressed by a single stem in Baima. That single stem regularly corresponds with the past stem of classical paradigms. Examples include: 'prick, thrust': Baima /tsŷ/, WT btsug or btsugs; 'split open': Baima /kē/, WT bkas.

'drink' (/ⁿdỳ/) does not regularly reflect the attested past stems of that verb ('thungs, btungs),

Table 6

 6 In spite of the drastic simplification of the original complex OT rhyme structure in Baima (see Tables A.2 and A.4), Baima alternating verbs unmistakably reflect both regular and irregular OT ablaut. Table7provides some examples.

	stem has the suffix -s in most paradigms. ("X-" in the past and imperative stems in paradigms
	9-12 stands for a devoicing prefix, cf. Beckwith 1996, as in 'block, obstruct': the past stem
	*bXgag > bkag, the imperative stem *Xgogs > khog.) In addition, some verbs with four stems
	also show ablaut. The regular patterns include a-a-a-o (as in 'look': lta, bltas, blta, ltos); e-a-

. Regular affixal paradigms in OT verbs

(adapted from Hill 2010: xix)

As shown in Table

6

, the present stem may have the prefixes '-and g-, and the suffix -d. The past stem has the prefix b-in all but one paradigm (1, "weak verbs") and the suffix -s in most paradigms. The future stem has the prefixes b-, and d-and no suffixes. Finally, the imperative a-o (as in

'do': byed, byas, byas, byos); o-a-a-o (as in 'put, place': 'jog, bzhag, gzhag, zhog)

.

The irregular ablaut pattern, viz., a-o-a-o, is limited to just four verbs, including 'eat

' (za, zos, bza', zo) and 'chew, gnaw' ('cha', 'chos, 'cha', 'cho ~ 'chos)

(Hill 2014: 622)

.

Table 7 .

 7 Examples of regular and irregular OT ablaut in Baima alternating verbs. Tibetan etymologies of Baima forms are highlighted in bold.

As shown in Table

7

, Baima 'look' reflects the a-a-a-o ablaut; 'put, place' reflects the o-a-a-o ablaut; 'take out, dredge' reflects the e-a-a-o ablaut; while Baima 'eat', which represents a semantic extension from the OT verb 'chew, gnaw', reflects the irregular ablaut pattern a-o-ao.

On the other hand, most affixal OT morphology is lost in Baima. Regular sound change in Baima leads to the loss of all verbal prefixes but the prefix '-in the present stem, which is retained in Baima as prenasalization of the root initial (see Table

A

.1).

13

The suffixes -d and -s in the present and past stems are lost, as are all OT consonantal codas in general, transforming all closed syllables into open syllables and generating innovative vowels and diphthongs (see

Table A.4

). In particular, the suffix -s in the past and imperative stems, when added to an open rhyme, leads to the vowel quality and tone change. Examples include: (1) /ɲʉ̄/, the past/imperative stem of the verb 'buy' (corresponding with WT nyos); to compare, the non-past stem of that verb is /ɲɞ̂/ (WT nyo); (2) /tyʉ̄/ the past/imperative stem of the verb 'look' (corresponding with WT ltos); (3) /tʂē/, the past/imperative stem of the verb 'cut with scissors'

  A few exceptions can be noted, for instance, verbs 7-8 in TableB.2 (that is, 'grind' and 'weave, knit'). Tone change in the past/imperative stems of these verbs, both /tɑ̄/, rather than the regularly expected form /tɑ̂/ to correspond with WT btags, suggests that -s in the past/imperative forms may be analysed as a distinct suffixal element, which conditioned the mid level tone on that form. Additional examples include verbs 'push down', 'press', 'build, pile up', 'carry on the shoulder' in TableB.5. 15 Two possible exceptions are 'quake (earth)': Baima /sʰa̠ ̂ ŋɡî/, corresponding with WT sa 'guld; and /ʑʊ̂/ 'ride (a horse)', corresponding with WT bzhond (respectively, verbs 20 and 110 in Table B.5).

		present	past	non-past	past/imperative
	1	'-_	_C-s
				NCV
	Paradigm		OT		Baima

) The onset alternation type encompasses those verbs that have, on the one hand, the prefix '-in the present stem and, on the other hand, identical (closed) rhymes in both stems (see verbs in Table

B

.2). In that paradigm, the non-past stem of the verb is prenasalized in Baima, and the past/imperative stem is non-nasalized, while the vowel remains unchanged. (The tones in the two stems may be different depending on the historical onset type, see Table

A

.3.)

(2) The vowel alternation type encompasses those OT paradigms that do not have the prefix '-in the present stem or where the addition of the prefix '-is impossible for phonological reasons (for instance, in verbs with complex onsets, such as 'look': *'-lta > lta) (see verbs in Table

B

.3). Vowel alternation in the two stems results from the addition of the suffix -s to an open rhyme in the past stem or from the original OT ablaut.

(3) The third alternation type, which combines onset and vowel alternation, includes verbs that have the prefix '-in the present stem, OT ablaut and/or an open rhyme in the past stem (see verbs in Table

B

.3).

16

Table

8

schematically presents the related developments.

14 16 The forth possible pattern, that is, C1V(V)1/C1V(V)1, where the OT onsets and rhymes in both stems are identical or become identical through regular sound change, obviously leads to the merger of the two stems, hence resulting in verbs with one stem (or non-alternating verbs). Examples include: /ɲɛ̄/ 'sleep

', cf. WT nyal, nyal(d), nyal, nyol(d)

; /nɑ̄ ɲɛ̄/ 'listen', cf. WT rna (m)nyan, (m)nyan(d), (m)nyan, nyon(d) / mnyand; /sê/ 'kill', cf. WT gsod, bsad, gsad, sod. The fifth possible pattern with two different non-nasalized onsets and/or two different vowels in two stems, that is, C1V(V)1/C2V(V)2, is marginal and irregular, as in as in 'give', Baima non-past stem /ʒə̂/, past/imperative stem /ɕī/, corresponding with

WT sbyin, byin, sbyin, sbyin (see verb 5 in Table B.4

).

Table 8 .

 8 Regular changes to the OT patterns of stem formation in Baima verbs with two stems. Brackets indicate optional constituents.Table 9 presents some illustrative examples.

	Pattern of stem	Gloss	OT			Baima
	formation		present	past	N-PST	PST/IMP
		die	'chi	shi	n dʒ ʢ ə̂	ʃə̂
	NCV(V)1/CV(V)1 sell	'tshong	btsongs	ⁿdzù	tsū
		pick, pluck	'thog	btogs	ⁿd ʢ uɛ̂	tuɛ̂
		exchange	rje	brjes	ʒɛ̂	ʒè
	C1V1/C1V2	buy	nyo	nyos	ɲɞ̂	ɲʉ̄
		take out, dredge	'dren	drang	ⁿdʐē	tʂō
	NCV(V)1/CV(V)2 put, place	'jog	bzhag	n dʒuɛ̂	ʒɑ̂
		cut with scissors	'dra	dras	n dʐa̠ ̂	tʂē

Table 9 .

 9 Examples of changes to the regular OT affixal paradigms in Baima verbs with two past/imperative stem. The latter stem, /kē/, regularly corresponds with the WT past stem bkas, whereas the former stem, / ŋ ɡa̠ ̂/, would be the expected outcome if the underlying OT form had been *'ga rather than the attested present stem of this verb, 'gas. It is conceivable that the original WT pattern with the coda -s in both stems (that is, 'gas, bkas) has been reinterpreted in Baima as one, in which the coda -s in the past stem is reanalyzed as the past suffix -s (bka-s), leading to the back formation of the present stem without -s (viz., *'ga). Another example is the verb 'weigh with a steelyard' (see verb 4 in TableB.2) with the o-a-a-o ablaut in the classical paradigm('gyog, bkyags, bkyag, khyog). The non-past form of that verb in Baima, / n dʑɑ̂/, is at variance with the present stem 'gyog. It is conceivable that the non-past stem has been reinterpreted on the basis of the past/imperative stem of this verb, Baima /tɕɑ̂/, corresponding with WT bkyags. An analogical explanation may also account for the loss of the original suffix -d in the present stem of the verbs 'wash', 'divide', and 'plough', reproduced in Table 10.

	stems
	Among the three main patterns of stem formation that result from regular sound change, the
	first (that is, NCV(V)1/CV(V)1) and the second (that is, C1V1/C1V2) are numerically more
	common, accounting for 29 and 19 verbs respectively (see Tables B.2-3). The third pattern
	(viz., NCV(V)1/CV(V)2) is more marginal, accounting for only 6 verbs (see Table B.4).
	The few alternating verbs, in which one of the stems is at variance with the attested WT

stems, are open to interpretation in terms of analogical changes. Consider the following examples. The verb 'split open' (see verb 2 in Table

B

.4) has / ŋ ɡa̠ ̂/ as its non-past stem and /kē/ as its

Table 10

 10

. Examples of possible loss of the suffix -d in the present stem. "No." indicates the serial number of the verb in Tables B.3-4 in Appendix B. Baima forms that show irregular sound correspondences with attested WT stems are highlighted in gray. The would-be sources of irregular Baima forms are preceded by an asterisk and provided in the corresponding WT slot, separated from the attested stems by a semicolon.

For example, the paradigm of the verb 'divide' may have been changed by analogy with the high frequency verb 'speak', that is /dzʊ ̀/ 'speak' (IMP) : /dzɞ̂/ 'speak' (N-PST) :: /gʊ ̀/ 'divide' (IMP) : /gɞ̂/ 'divide' (N-PST), that is, replacing the form that the attested present stem bgod would have yielded regularly. 17

Table 11 .

 11 Table11provides some examples. Examples of alternating verbs in Zhongu together with their Tibetan etymologies in J.[START_REF] Hongkai | Is Baima a dialect or vernacular of Tibetan?[END_REF], compared to corresponding verbs in BaimaWe note that in addition to the tendency to eliminate a separate imperative stem of classical

	Gloss		Zhongu			WT			Baima
		N-PST	PST IMP	present	past	imperative N-PST PST	IMP
	eat < gnaw	ⁿtʃʰɐ	ⁿtʃʰi ⁿtʃʰo 'cha	'chas	'chos 18	n dʒ ʢ a̠ ̂	n dʒʊ ̀ n dʒ ʢ ɞ̂
	stay; sit	ⁿdə	dɛ	di	'dug	bsdad	sdod	n dy	dê	dyʉ̂

paradigms, Zhongu and Baima also share some other developments. These include the semantic extension from 'chew, gnaw' to 'eat'. Overall, that extension appears to be an areal development in several Tibetic varieties spoken in the neighborhood of Baima, including in addition to Zhongu, also Kun sngon, Chos.rje, and Zhangla or lCang.la (see Hua

[START_REF] Kan | Zangyu Songpanhua de yinxi he yuyin de lishi yanbian 藏語松潘話的音系和語音的歷史演變 [Sound system of Songpan Tibetan and its historical development[END_REF] J. Sun 2003: 834, footnote 41)

.

Baima and Zhongu also share the suppletive paradigm of the verb 'sit; stay', where the past stem bsdad and the imperative stem sdod are suppletive for the verb 'dug. The same suppletive paradigm has also been reported for a few other Amdo varieties of the historical Sino-Tibetan borderlands, including Ndzorge (Sichuan, J. Sun 1993: 974, note 34) and Nangchenpa

(Qinghai, Causemann 1989: 93, cited from Zeisler 2004: 564)

.

  Table A.1 summarizes major trends in the development of Baima onsets.

	Historical	OT	OT initial	Baima	Example
	onset type	preinitial			Gloss	WT	Baima
	breathy	oral	voiced stop, affricate, fricative	D ̤ > D	stone	rdo	dɞ̂
		nasal	voiceless aspirated stop, affricate ⁿD ̤ > ⁿD ʢ fly (v.)	'phur	m b ʢ û
		oral, nasal	nasal, liquid, approximant	S̤ > S ʢ	pus	rnags	n ʢ ɑ̂
	plain	∅-	voiceless aspirated stop, affricate	Tʰ	hempen cloth	thags	tʰɑ̂
	or		voiceless unaspirated fricative		tooth	so	sʰɞ̂
	non-breathy		voiceless unaspirated stop,		pillar	ka ba	kɑ̄
			affricate
			voiced stop, affricate, fricative	T	poison	dug	tŷ
		oral	voiceless unaspirated stop,		mark, sign	rtags	tɑ̂
			affricate
		nasal	voiced stop, affricate	ⁿD	insect	'bu	m bû
		∅-	nasal, liquid, approximant	S	forest	nags	nɑ̂

  Table A.2 provides some illustrative examples.

	non-tense (lax)		snow	kha ba	kʰɑ ̀
	lower pitch	codas -m, -n, -ng	to be dry	skam	kō
	longer duration		bottom part	gdan	dɛ ̀
			lap; bosom	pang	pō
		codas -l, -s	to sleep	nyal	ɲɛ̄
			rice	'bras	ɳ ɖɽē
	Table A.2. Major trends in the development of Baima vowels
	Phonation type
	Vowel duration	OT rhyme		Example
	F0		Gloss	WT	Baima
		open	mouth	kha	kʰa̠ ̂
	tense	coda -r	four	bzhi	ʒə̂
	shorter duration		year	lo	jɞ̂
	higher pitch	codas -b, -d, -g	needle	khab	kʰʉ̂
			voice; language	skad	kê
			to be hungry	ltogs	tuɛ̂
		coalesced syllables	food	za ma	sō

20

OT rhymes with the coda -r have the same reflexes as syllables with zero coda, for which reason it is likely that -r was lost early in the history of Baima

(Huang & Zhang 1995: 99)

.

  Table A.3 summarizes tonal developments in Baima.

		Stage 1	Stage 2			Example
	OT rhyme	Phonation	Baima onset	Tone Gloss	WT	Baima
	-b, -d, -g		(historically breathy)		village	sde	dɛ̂
	open (-r)	tense	epiglottalized		lips; beak	mchu	ⁿdʒ ʢ û
		shorter duration (historically plain)	H	mouth	kha	kʰa̠ ̂
		higher pitch	voiceless aspirated		tooth	so	sʰɞ̂
			voiceless non-aspirated		to dig (IPFV) rko	kɞ̂
			voiceless non-aspirated	M	pillar	ka ba	kɑ̄
	-m, -n, -ng, -s, -l lax	(historically breathy)		bottom part	gdan	dɛ ̀
	coalesced	longer duration	voiced obstruent, sonorant	L	to jump	mchong ⁿdʒù
	syllables	lower pitch	(historically plain)		snow	kha ba	kʰɑ ̀
			voiceless aspirated		charcoal	sol	sʰɛ ̀
	Table A.3. Tonal developments in Baima

Baima verbs with their suggested etymologies

  This section regroups all verbs in our data. The alternating verbs are organized by the number of stems. Verbs with three stems are listed first (TableB.1), followed by verbs with two stems (Tables B.2-4). Verbs with two stems are further organized by alternation type: onset alternation first (TableB.2), followed by vowel alternation (TableB.3), and by a combination of onset and vowel alternation after that (TableB.4). Non-alternating verbs are listed in TableB.5. TableB.6 lists loan verbs from Chinese and periphrastic constructions with the auxiliary verb 'do; make' in our data.

	a̠	ʉ	e	ɑ	ɛ	o	o	iɛ	e / ɛ
	i ə	i	i	i	e	e	i	ə	ə / i
	u u	y, u	i, y	y	e	u	u	ə	y
	e ɛ	e	e	e	e	e	e	e / ɛ e
	o ɞ	ɞ	e (after labials), ʉ uɛ	ʊ	u	o	i	e (after labials), yʉ / ʊ
	Table A.4. Baima reflexes of OT rhymes
	Appendix B.

Table B .

 B 3. Verbs with two stems differentiated by vowel alternationOne more verb with two stems, 'drink', has identical non-past and imperative forms, both / n dù/, corresponding, respectively to WT 'thung and 'thungs. The past stem of this verb, Baima / n dỳ/ does not regularly correspond with the attested past stem of this verb 'thungs.Finally, one verb with two stems, 'flow (water'), has a suppletive paradigm. The non-past stem of this verb is / n dʑɞ̂/, likely reflecting WT 'gro 'go'. The past stem of this verb is /ɕʰɑ ̀/ (homophonous with the past stem of the verb 'sweep', see B.2.15). It may be etymologically related, albeit in an irregular fashion, to WT phyin, the past stem of the verb gshar 'go successively, again and again, move one after the other, follow in succession'. TableB.5 lists non-alternating verbs in our data. As can be seen from that table, most non-alternating verbs correspond with verbs that are alternating in OT. In the majority of cases, the originally distinct stems merge in Baima due to regular sound change (see footnote 16). In the table, attested stems forms that match sound correspondences between Baima and WT are highlighted in bold. In one case, 'cry, weep' (B.5.37), a non-alternating verb results from an ongoing elimination of stems. That verb is recorded with two stems in H.Sun et al. (2007) (see

	No. Gloss		Baima		WT
				N-PST	PST/IMP	present	past	imperative
	1	dig, scoop		kɞ̂	kyʉ̄	rko	brkos
	2	kick		(dɞ̂tɞ̂) dʑɑ̂	dʑʉ̂	(rdogtho) rgyag	brgyab(s)
	3	mend		(ɑ ̀mba̠ ̂) dʑɑ̂	dʑʉ̂	(lhanba) rgyag	brgyab(s)
	4	divide		ɡɞ̂	gʊ ̀	bgod; *bgo	bgos
	5	exchange		ʒɛ̂	ʒè	rje	brjes
	6	buy		ɲɞ̂	ɲʉ̄	nyo	nyos
	7	throw, cast		( n dɐ̂) m bè	m bò	(mda) 'phen(d)	'phangs
	8	cut; mow		tʂa̠ ̂	tʂē	'breg/breg; *bra?	bregs
	9	plough		mɞ̂	mē	rmod; *rmo	rmos
	10	jump		tsɛ̂	tsē	rtse	brtses
	11	ache, be painful	tsʰa̠ ̂	tsʰê	tsha	?
	12	herd		n dz ʢ ɞ̂	n dzʊ ̀	'tsho	'tshos
	13	close, shut (door) 24 zɞ̂	zʊ ̀	bzo?	bzos?
	14	take, hold		jē	jō	len	blangs; *langs
	15	look		ta̠ ̂	tyʉ̄	lta	ltos
	16	split firewood	sɛ̂	sē	gse	gses
	17	give birth		sɞ̂	syʉ̄	gso	gsos
	18	rest; dry in the sun ʃɞ̂	ʃyʉ̄	sro	bsros
		No.	Gloss		Baima	WT
					N-PST	PST/IMP	present	past
		1	wash		n dʑ ʢ û	tɕȳ	'khru	bkrus
		2	split open	ŋ ɡa̠ ̂	kē	'gas; *'ga	bkas
		3	cut with scissors	n dʐa̠ ̂	tʂē	'dra	dras
		4	take out; dredge	ⁿdʐē	tʂō	'dren	drang
		5	give		ʒə̂	ɕī	sbyin; *sbyi? 25	byin
		6	put; place	n dʒuɛ̂	ʒɑ̂	'jog	bzhag
	Table B.4. Verbs with two stems differentiated by a combination of onset and vowel alternation

24

In terms of regular sound correspondences, this verb matches the WT verb 'do'.

25

The non-past form of this Baima verb, viz., /ʒə̂/, is homophonous with the numeral 'four', WT bzhi.

Table 2 )

 2 , but it has only one stem in our data (viz., /ŋû/). TableB.5. Non-alternating Baima verbs with their suggested etymologies TableB.6 verbs lists the 15 non-alternating verbs that are borrowed from Chinese and the 6 periphrastic expressions that consist of a noun or a verb followed by the (alternating) auxiliary verb 'do; make'.

	No.	Gloss	Baima		WT
			N-PST / PST/ IMP	present	past		imperative
	1	borrow (money)	ɕī	skyi	bskyis		skyis
	2	spit	ɕŷ	skyug	skyugs		skyugs
	3	vomit	ɕŷ	skyug	skyugs		skyugs
	4	grow (in height)	ɕê	skyed	bskyed		skyed
	5	stretch out, extend	tɕō	rkyong	brkyangs		rkyongs
	6	fear, be afraid	ɕa̠ ̂ or tɕa̠ ̂	skrag; *skra	skrag(s); *skra	skrags; *skra
	7	swell up	ɕō or tɕō	skrang	skrangs		skrangs
	8	stir	tɕŷ	dkrug	dkrugs		dkrugs
	9	dry up, dry out	kō	skam	bskams, skam	skams
	10	smear	kŷ	skud	bskus		skus
	11	apply ointment	kŷ	skud	bskus		skus
	12	make noodles < boil, cook	kî	skol	bskol		skol
	13	lose (a battle) < shrink, recoil?	kʰô	'khum?	'khums?		'khums?
	14	carry on the back	kʰû	'khur	khur(d), bkurd	khur(d)
	15	fall ill < be subdued,	kʰì	'khul	khul		khul
		overwhelmed?
	16	run	tɕŷ	'khyus	'khyus, khyus	khyus
	17	pull, lead	kʰî	khrid	khrid		khrid
	18	nod (head)	( ŋ ɡɞ̂) ŋuɛ̂	(mgo) 'gug(s)? 26 bkug		khug
	19	squat	kū	dgum	bkums		khum(s)
	20	quake (earth)	sʰa̠ ̂ ŋgî	sa 'gul	sa 'gul(d)		sa 'gul
	21	crack between the teeth	kuɛ̂	'gog	bkog		gog, khog
		(seeds)
	22	shell, peel	kuɛ̂	'gog	bkog		gog, khog
	23	laugh	ga̠ ̂	dgod, rgod	b(r)gad,	rgod;	dgod, rgod
					*b(r)ga
	24	cross (e.g. a river)	gɛ ̀	rgal	brgal		rgol
	25	straddle	kô dʑò	(gom) rgyang	brgyang-s?		rgyangs
	26	throw, cast	ʑʉ̂	rgyab	brgyab		rgyob
	27	transform, change	ɲ dʑỳ	'gyur	'gyur		'gyurd
	28	lift, raise (head)	( ŋ ɡɞ̂) ʑa̠ ̂tʃa̠ ̂	'gyogs/'gyogs	(mgo) yar bkyags khyogs

26 We tentatively propose that this verb may reflect WT 'gugs 'to bend, to cause to bend'. This is based on the observation that the expression mgo 'gugs is used in the sense of 'nod head' in several Tibetic varieties spoken in the vicinity of Baima. These include the Zhongxinrong / gtsang chen rong variety of 'ba' thang Tibetan, Thebo, and the Bola 博拉话 / 'bo ra variety of bla brang Tibetan. Table B.6. Loan verbs and periphrastic expressions with the auxiliary verb 'do; make' in our data

Note that similar to Old Tibetan and modern Tibetic languages, prohibitive imperative in Baima is formed by combining the negator /ma̠ / with the imperfective stem of the verb. Examples include: /ma̠ ̂ n dʒ ʢ a̠ ̂/ 'do not eat', /ma̠ ̂ ŋû/ 'do not cry', /ma̠ ̂ tɕa̠ ̂/ 'don't be afraid'.

The imperative form of 'sit; stay' should read /de⁴²/, that is with tone 42, as elsewhere in[START_REF] Bufan | Baima zhishu wenti yanjiu 白马话支 属问题研究 [A study of the genetic affiliation of Baima[END_REF].

Interestingly, some Tibetic varieties spoken in the border areas between Sichuan, Qinghai, and Gansu provinces exceptionally maintain the WT distinction between a separate present stem and a separate future stem. This is the case in Gserpa (J.Sun 2006: 115). Khalong (J.Sun 2007: 327), on the other hand, evidences WT future stems as sources of imperfective stems in some verbs.

We note that the loss of the past stem of that verb and the usurpation of that stem by the imperative stem is likely a recent development in Baima. Nishida & H.[START_REF] Tatsuo | Hakuba yakugo no kenkyū: Hakuba no kōzō to keitō 《白馬譯語の研究: 白馬語の構造と系统》 [A study of the Baima-Chinese vocabulary 'Baima yiyu': the structure and affiliation of the Baima language[END_REF] and H.Sun et al. (2007) record the verb 'look' as having three stems, namely, (i) the non-past stem /ta¹³/⁵³/ (which regularly corresponds with WT lta), (ii) the past stem /tɛ³⁵/ (which regularly corresponds with WT bltas), and (iii) the imperative stem /tø³⁵/ (which regularly corresponds with WT ltos). Conversely, this verb has only two stems in Huang & Zhang's data (see Table1) and in our data, namely, (i) the non-past stem /ta̠ ̂/ (corresponding with WT lta) and (ii) the past/imperative stem /tyʉ̄/ (corresponding with WT ltos).

Note that the major sound correspondences between Zhongu and OT, as described in J.[START_REF] Hongkai | Is Baima a dialect or vernacular of Tibetan?[END_REF], rather suggest 'cho as the underlying form for the imperative stem of this verb, as is also the case in Baima. Specifically, according to J.Sun (2003: 790), OT os corresponds to Zhongu /i/, while OT o corresponds to Zhongu /o/.

This is based on a similar shift from grang 'be cold; become cold' to 'blow (wind)' in the Tibetic varieties neighbouring Baima, including 'bo ra (/lang cca/ is 'the wind blows; to blow (wind)'), Thebo (/cca/ or /tɕa/ 'to blow (wind)'), and Cone (/lʉː H tɕɑː L / 'the wind blows; to blow (wind)').

Appendix A. Baima synchronic and historical phonology

This study adopts the phonological analysis of Pingwu Baima (hereafter Baima), as detailed in [START_REF] Chirkova | Tonal developments in Baima[END_REF] and Chirkova (2021, under review). Compared to the previous phonological analyses of Baima in Nishida & H. [START_REF] Tatsuo | Hakuba yakugo no kenkyū: Hakuba no kōzō to keitō 《白馬譯語の研究: 白馬語の構造と系统》 [A study of the Baima-Chinese vocabulary 'Baima yiyu': the structure and affiliation of the Baima language[END_REF], [START_REF] Bufan | Baima zhishu wenti yanjiu 白马话支 属问题研究 [A study of the genetic affiliation of Baima[END_REF], and H. Sun et al. (2007); [START_REF] Chirkova | Tonal developments in Baima[END_REF] and Chirkova (2021, under review) (i) additionally recognize phonation contrasts in consonants (non-epiglottalized, epiglottalized) and vowels (tense, modal, lax), and (ii) propose a new analysis of the tonal system, whereby contrastive tonal categories in Baima are described as typified not only by fundamental frequency (pitch height, slope), but also by contrastive phonation.

The structure of the Baima syllable is (C)V(V), where C (which is optional) can be any phonemic consonant, and V stands for vowel. The segmental inventory includes:

(i) 57 consonant phonemes, of which 35 are non-epiglottalized (/p pʰ t tʰ k kʰ ts tsʰ tʃ tʃʰ tɕ tɕʰ ʈɽ ʈɽʰ s sʰ ʃ ʃʰ ɕ ɕʰ x m b ⁿd ŋ ɡ ⁿdz ɲ dʑ ɳ ɖɽ m n ɲ ŋ r j l w/) and 22 are epiglottalized (/b d ɡ dz dʒ dʑ ɖɽ z ʒ ʑ ɣ m b ʢ ŋ ɡ ʢ ⁿdz ʢ ⁿdʒ ʢ ɲ dʑ ʢ m ʢ n ʢ ɲ ʢ ŋ ʢ j ʢ l ʢ/ ) (note that in non-nasalized voiced obstruents, epiglottalization is contingent on voicing and for that reason, not marked in transcriptions) (ii) 15 vowel phonemes, including 11 monophthongs (/i e ɛ ʊ ə ʉ u ɞ o a̠ ɑ/) and 4 diphthongs (iɛ yʉ uɛ ua̠ ).

Baima has three contrastive tonal categories: high falling, mid, and level, as in / ŋ ɡuɛ̂/ 'bark (dog)', / ŋ ɡuɛ̄/ 'pan', / ŋ ɡuɛ / 'downstairs'.

The simple (C)V(V) syllable structure in Baima represents considerable reduction and simplification of the complex OT syllable structure, that is, (b)(C)C(M)V(C)(s/d), where C stands for consonant, M for medial and V for vowel. The main developments of Baima onsets are conditioned by the presence or absence of OT prefixes. Unprefixed voiceless stops and affricates remain unchanged and non-epiglottalized, whereas unprefixed voiceless fricatives become aspirated. Unprefixed voiced obstruents become devoiced and non-epiglottalized. The major trend for oral prefixal consonants ( g-, d-, b-, r-, l-, s