Southwestern Tai
Southwestern Thai
Southeast Asia
Linguistic classificationKra–Dai
Proto-languageProto-Southwestern Tai (Proto-Thai)
  • Southern Thai
  • Central–Eastern Thai
Distribution of the Southwestern Tai languages.

The Southwestern Tai or Thai languages are a branch of the Tai languages of Southeast Asia. Its languages include Central Thai (Siamese), Northern Thai (Lanna), Lao (including Isan), Shan and others.


The internal classification of the Southwestern Tai dialects is still not well agreed on.

Chamberlain (1975)

Chamberlain (1975) divides Southwestern Tai into 4 branches.[1]

Chamberlain based his classification on the following phonological patterns. (Note: For an explanation of the notation system for Tai tones, see Proto-Tai language#Tones.)

  1. /p/ vs. /ph/
  2. tone *A column split/merger pattern
  3. tone *BCD columns split/merger patterns
  4. B-DL tonal coalescence
Proto-Southwestern Tai

The Tai Muong Vat of Yen Chau, Vietnam is a PH-type language like Lao, even though it is geographically surrounded by Black Tai (Theraphan 2003; Chamberlain 1984).[2][3]

Edmondson & Solnit (1997)

Edmondson & Solnit (1997) divide the Southwestern Tai dialects into two major subgroups. According to this classification, Dehong Tai and Khamti are the first languages to have split off from the Southwestern Tai branch.[4]

  1. Northern: Tai Nua = Shan-Tayok (Chinese Shan), Khamti
  2. Southern: Burman Shan ("Shan proper"), all other Southwestern Tai

A transition zone between the Northern and Southern groups occurs among the Tai languages (including Tai Mau) around the Burma-China border region of Mangshi, Namhkam, and Mu-se near Ruili.

This bipartite division of Southwestern Tai is argued for by Edward Robinson in his paper "Features of Proto-Nüa-Khamti" (1994). The following features set off the Nüa-Khamti group from all the other Southwestern Tai dialects.

  1. Labialized velar stops have become velar stops.
  2. Tripartite split of the A tone A1-23-4
  3. Merger of A23 and B4
  4. The low vowels /ɛ/ and /ɔ/ have merged with /e/ and /o/, respectively.
  5. *ʔb > m

Luo (2001)

Luo Yongxian (2001) also recognizes the uniqueness of Dehong Tai (Tai Nuea), but argues for that it should be placed in a separate Northwestern Tai branch with Southwestern Tai as a sister branch.[5] Luo claims that the Northwestern Tai branch has many Northern Tai and Central Tai features that are not found in Southwestern Tai. His proposed tree for the Tai branch is as follows.

Pittayaporn (2009)

See also: Tai languages § Pittayaporn (2009)

According to Pittayaporn (2009:301), Southwestern Tai (his subgroup Q) is defined by a phonological shift of *kr- → *ʰr-.[6]

Pittayaporn (2014) also suggests that Southwestern Tai began to disperse southward after the 7th century C.E. but before the 11th century C.E. (between 700 and 1000 C.E., during the late Tang dynasty or early Song dynasty), as evidenced by loanwords from Late Middle Chinese.[7]

Pittayaporn (2018)[8] recognizes two branches within Southwestern Tai, namely Eastern and Western. The Eastern branch consists of the closely related languages Black Tai, White Tai, and Red Tai, while the Western branch is much more internally diverse. The Western branch also contains a Southern group consisting of Thai and Lao.

Southwestern Tai

Pittayaporn, et al. (2018)[9] note that following sound changes from Proto-Southwestern Tai (PSWT) to the Tai varieties represented in the Sukhothai and Ayutthaya inscriptions, and conclude that the Sukhothai and Ayutthaya inscriptions in fact represent the same language.

  1. the merger of dorsal obstruents
  2. the merger of PSWT *aɯ and *aj
  3. the merger of PSWT *ɲ-, *j- and *ʔj-
  4. the loss of voicing distinction in sonorants
  5. *ɓl- > d-
  6. *kʰr- > kʰ-
  7. *ʰr- > h-


Southern Thai (Pak Thai) is often posited to be the most divergent; it seems to retain regular reflexes of early tonal developments that were obscured in the other (Central–Eastern) languages. The reconstructed language is called Proto-Thai; cf. Proto-Tai, which is the ancestor of all of the Tai languages.

The following tree follows that of Ethnologue[10]

According to Ethnologue, other Southwestern dialects are Tai Ya (China), Pu Ko (Laos), Pa Di (China), Tai Thanh (Vietnam), Tai Long (Laos), Tai Hongjin (China), Yong (Thailand). It is not clear where they belong in the classification above. Ethnologue also lists under Tai, without further classification, Kuan (Laos), Tai Do (Viet Nam), Tai Pao (Laos), and Tay Khang (Laos). Geographically these would all appear to be Southwestern.[11]

Ethnologue also includes Tày Sa Pa (Sapa) of Vietnam, which Pittayaporn excludes from Southwestern Tai but classifies as the most closely related language outside of that group. Pittayaporn also includes Yoy, which Ethnologue classifies as a Northern Tai language.[11]

Further reading


  1. ^ Chamberlain, James R. 1975. "A new look at the history and classification of the Tai dialects." In J. G. Harris and J. R. Chamberlain, eds, Studies in Tai Linguistics in Honor of William J. Gedney, pp. 49–60. Bangkok: Central Institute of English Language, Office of State Universities.
  2. ^ Chamberlain, James R. 1984. "The Tai dialects of Khammouan province: their diversity and origins". Science of language, 4:62–95.
  3. ^ Theraphan L-Thongkum. 2003. "The Tai Muong Vat do not Speak the Black Tai Language". In Manusya: Journal of Humanities, Special Issue 6, 74–86. Bangkok: Chulalongkorn University Press.
  4. ^ Edmondson, Jerold A., Solnit, David B., authors. 1997. "Comparative Shan." In Comparative Kadai: The Tai branch, Jerold A. Edmondson and David B. Solnit (eds.). pages 337–359. Summer Institute of Linguistics and the University of Texas at Arlington Publications in Linguistics 124. Dallas: Summer Institute of Linguistics and the University of Texas at Arlington.
  5. ^ Luo Yongxian. 2001. The Hypothesis of a New Branch for the Tai Languages. University of Melbourne.
  6. ^ Pittayaporn, Pittayawat. 2009. The Phonology of Proto-Tai. Ph.D. dissertation. Department of Linguistics, Cornell University.
  7. ^ Pittayaporn, Pittayawat. 2014. "Layers of Chinese Loanwords in Proto-Southwestern Tai as Evidence for the Dating of the Spread of Southwestern Tai". In Research Findings in Southeast Asian Linguistics, a Festschrift in Honor of Professor Pranee Kullavanijaya. Manusya, Special Issue 20. Bangkok: Chulalongkorn University Press.
  8. ^ Pittayaporn, Pittayawat (2018). Subgroup structure of Southwestern Tai based on early phonological innovations. Paper presented at the 28th Annual Meeting of the Southeast Asian Linguistics Society, held May 17–19, 2018 in Kaohsiung, Taiwan.
  9. ^ Pittayawat Pittayaporn, Sireemas Maspong, Shinnakrit Tangsiriwattanakul, and Yanyong Sikkharit (2018). The genetic relationship between Sukhothai and Ayutthaya. Paper presented at the 28th Annual Meeting of the Southeast Asian Linguistics Society, held May 17–19, 2018 in Kaohsiung, Taiwan.
  10. ^ "Southwestern". Ethnologue. Retrieved 2020-06-29.
  11. ^ a b Lewis, M. Paul (2009), Ethnologue: Languages of the World (16 ed.), SIL International