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) divides Southwestern Tai into 4 branches.

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.)

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).

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.

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.