The Palaungic Branch
The Palaungic (or Palaung-Wa) branch is quite diverse: it includes more than 30 languages comprising at least three primary divisions, and showing great typological diversity.  It is likely that the three Palaungic subgroups correspond to three closely related MK proto-languages that dominated the Shan State and Yunnan regions before the recent period of great migrations out of Southern China.
    Palaungic communities are spread over a wide area that overlaps Thailand, Burma, China and Laos.  They are generally found in small discontiguous pockets surrounded by other ethnic groups: the Tai, Meo and Tibeto-Burmans who repeatedly colonised the upper Mekong and Salween valleys over the last millennium or so. 
    While many Palaungic languages are poorly documented and/or endangered, some useful descriptions are available, and a substantial comparative reconstruction of one sub-branch (Waic - Diffloth 1980) has been published.  Data is becoming increasingly available, thanks to field research in northern Thailand and southern China.  Chinese researchers have published a number of language descriptions with marvelous phonetic detail.  They provide lexicons arranged according to standardised semantic categories, and are readily usable even to researchers without a good reading command of Chinese. 
Subgroups in the Palaungic branch
Palaungic can be divided into at least 3 subgroups: Waic, Angkuic, and Palaung-Riang Historically Palaungic appears to have merged the PMK implosive and voiced stop series into a single voiced series, which was then devoiced in almost all daughters.  An exception is found within Palaung-Riang: Rumai and Ta-ang preserve *voiced stops.
    Along with devoicing, many Palaungic languages developed breathy versus clear vowel registers or even 2 tone systems.  Angkuic developed tones, but these were conditioned by different factors (see below). It is even possible that at least one Palaungic language, Riang, may even maintain the old *implosives as a distinct (although merely voiced) series.
    The most distinct phonological variation that divides Palaungic from the rest of MK is the regular merger of *s and *h.  In Palaung-Riang and Waic the outcome of the merger was /h/, while in Anguic it was /s/.
the Palaung-Riang subgroup
As noted above, two of this sub-group's languages are particularly conservative: Rumai and Ta-ang. The rest have devoiced all their voiced obstruents, with associated register and other vowel effects.  Loss of vowel length distinction is also common, and seems to be a widespread areal characteristic. 
the Waic subgroup
Perhaps the best-known of the Palaungic languages is Wa (Paraok), on which there are numerous publications, and a bible translation (Young 1934).  The Wa Dictionary Project at SOAS is documenting Wa extensively.  The project seeks to compile a Wa/Burmese/Chinese/English Dictionary containing up to 10,000 etyma.  Chinese researchers have also been busy, and have published dictionaries, text collections and numerous papers. 
    The term "Wa" tends to be used for various dialects, so it is important to distinguish the particular variety a given source refers to, especially for comparative purposes.  Waic in general devoiced stops, and in most dialects contrastive breathy phonation followed, helping to distinguish vowels following the previously voiced series.  Paraok further underwent a Khmer-like split in the vowel system, while in Lawa some dialects either lost breathy phonation, or reflect it as aspiration of the initial consonant. 
the Angkuic subgroup
Finally, the Angkuic sub-group is especially fascinating, because it has developed contour tones rather than registers.  These languages are spoken by very small and widely placed communities in Yunnan, Myanmar, Laos and Thailand.  Exceptionally endangered, they were first known from word lists collected a century ago, e.g.: Lefèvre-Pontalis (1892, 1896), d'Orléans (1898), Scott & Hardiman (1900), Davis (1909).  More recently Svantesson (1988) presented a short but excellent description of the phonetics and historical development of U as it is spoken in the village of Pa Xep in Yunnan.
    U has undergone rather extreme phonetic changes in the course of its development.  These include:
  • *voiced stops > voiceless, while *voiceless stops > aspirated (so called "Germanic type shift")
  • loss of distinctive vowel length
  • shift of both final velar stop and *-s to a pharyngeal fricative
  • shift of final nasal after *short vowels to corresponding oral stops<
  • shift of final velar fricative to a nasalised low central vowel [ã]
  • development of four tones
The tone system emerged approximately as follows:
  • Low tone: from *syllables with short vowel and sonorant coda; open syllable with non-high vowel
  • High tone: from *syllables with short vowel and stop or -s coda; long vowel and a voiceless obstruent among the prevocalic segments; open syllable with high vowel
  • Rising tone: from *syllables with long vowel and stop or -s coda
  • Falling tone: from *syllables with long vowel and sonorant coda if all prevocalic segments are sonorant
The role of vowel length in U tonogenesis is unusual, if not unique.  That aside, the evidence from U tones confirms that etymological MK vowel length must be reconstructed for Proto-Angkuic, and thus for Proto-Palaungic as well.
References and further reading
  • Chén, X-M. et. al. 1986. Da-angyu jianzhi. Beijing, National Minorities Press. (A description of the Ta-ang language, in Chinese).
  • Davies, Henry Rudolph. 1909. Yün-nan: the link between India and the Yangtze. Cambridge, Cambridge University Press.
  • Diffloth, Gérard. 1980. The Wa Languages. Linguistics of the Tibeto-Burman Area. Vol. 5/2. Berkeley: University of California.
  • Diffloth, Gérard. 1991. Palaungic vowels in Mon-Khmer perspective. In Davison ed. Austroasiatic Languages, essays in honour of H. L. Shorto. SOAS, University of London.
  • Drage, Godrey. 1907. A few notes on Wa. Rangoon, superintendent, Government Press.
  • Izikowitz, K. G. 1951. Lamet: Hill peasants in French Indochina. Etnologika studier, 17. Götenborg.
  • Lefèvre-Pontalis, Pierre. 1892. Nores sur quelques populations du nord de l'Indochine. Journal Asiatique 8.19:237-69.
  • Lefèvre-Pontalis, Pierre. 1896. Nores sur quelques populations du nord de l'Indochine (2e série). Journal Asiatique 9.8:129-303.
  • Li, Dao Yong, Nie Xi Zhen and Qiu E Feng. 1986. Bulangyu jianzhi. Chinese Academy of Social Sciences, Beijing. (A description of Bulang (Lamet). )
  • Luce, Gordon H. 1965. Danaw, a dying Austroasiatic language. Lingua 14:98-129.
  • Milne, Leslie. 1921. An Elementary Palaung Grammar. Oxford, Clarendon Press.
  • Milne, Leslie. 1931. A dictionary of English-Palaung and Palaung-English. Rangoon, Superintendent, Government Printing and Stationary.
  • Mitani, Yasuyuki. 1966. Descriptive Study of the Lawa language (Bo Luang district). Tônan Ajia Kentyû (South East Asian Studies) 4.2: 40-62.
  • Mitani, Yasuyuki. 1972. A short vocabulary of Lawa. Tônan Ajia Kentyû (South East Asian Studies), 10.1: 131-68.
  • Mitani, Yasuyuki. 1972. Studies in the Lawa phonology. Tônan Ajia Kentyû (South East Asian Studies), 10.2: 174-96.
  • Mitani, Yasuyuki. 1977. Palaung dialects: a preliminary comparison. Tônan Ajia Kentyû (South East Asian Studies), 15.2: 193-212.
  • Mitani, Yasuyuki. 1979. Vowel Correspondences between Riang and Palaung. Studies in Thai and Mon-Khmer Phonetics and Phonology in Honour of Eugénie J.A. Henderson. Chulalongkorn University Press, Bangkok, pp142-50.
  • d'Oréans, Henri. 1898. Fron Tonkin to India by the sources of the Irawadi. Translated by Hamley Bent. London, Methuen.
  • Paulsen, Debbie Lynn. 1989. A Phonological Reconstruction of Proto-Plang. M.A. Thesis, The University of Texas at Arlington.
  • Proschan, Frank. 1996. A Survey of Khmuic and Palaungic Languages in Laos and Vietnam. Pan-Asiatic Linguistics, 3: 895-919.
  • Ratanakul, Suriya. 1986. Lawa-Thai Dictionary. Institute of Language and Culture for Rural Development, Mahidol University, Salaya.
  • Ratanakul, Suriya. 1987. Thai - Lawa Dictionary. Institute of Language and Culture for Rural Development, Mahidol University, Salaya.
  • Schmidt, Pater Wilhelm. 1904. Grundzüge einer Lautlehreder Khasi-Sprache in ihren Beziehungen zu derjenigen der Mon-Khmer-Sprachen. Mit einem Anhang: die Palaung-Wa-, und Riang-Sprachen des mittleren Salwin. Abh. Bayrischen Akademie der Wissenschaft, 1.22.3:677-810.
  • Scott, James George and J.P. Hardiman. 1900. Gazetteer of Upper Burma and the Shan States 1.1. Rangoon, Superintendent, Government Printing.
  • Shorto, Harry L. 1960. Word and syllable paterns in Palaung. Bulletin of the School of Oriental and African Studies 23:544-57.
  • Shorto, Harry L. 1963. The Structural pattern of northern Mon-Khmer languages. In H.L. Shorto (ed.), Linguistic Comparison in South-East Asia and the Pacific. pp 45-61.
  • Svantesson, Jan-Olof. 1988. U. Linguistics of the Tibeto-Burman Area, 11.1:64-133.
  • Watkins, Justin. 2002. The Phonetics of Wa. Canberra, Pacific Linguistics 531.
  • Wenk, K. 1965. Drei Lawa vokabularien aus Nordthailand. Oriens Extremus 12:107-127.
  • Young, M. V. 1934. Lai Yohan, Gospel of John in Wa. Rangoon, American Baptist Mission Press.
  • Zhou Zhizhi and Yan Qixiang. 1983. Approaching the Consonantism of Ancient Wa from Phonological Correspondences Among the Dialects of Contemporary Wa. In Yuyan Yanjiu No.1. Beijing, Institute of Nationality Studies, Chinese Academy of Social Sciences.
  • Zhou Zhizhi et. al. 1991. Pug lai cix ding yiie sindong lai Vax mai Hox. Kunming, Yunnan Minorities Press. (A Concise Dictionary of Wa and Chinese)