Western Sino-Tibetan

The core of Western Sino-Tibetan linguistic diversity was likely in Assam and northern Myanmar, but this has been obliterated by the expansion of the Sal languages - Bodo-Garo languages in Assam and Jingpho-Luish languages in northern Myanmar.

Once Tibetan loanwords are excluded, the Sino-Tibetan languages of Nepal tend to show the most similarities with the Central Sino-Tibetan languages of Northeast India and northern Myanmar.

Western Sino-Tibetan split off from Eastern Sino-Tibetan, but West ST is not a proper branch. Rather, it is a linkage resulting from streams of multiple migrations. The plains of Assam would have served as a nucleus for linguistic convergence and then dispersal of Western Sino-Tibetan branches further west into Bhutan and Nepal, northward into Arunachal (Tani), and southward into the Naga Hills (Central Sino-Tibetan, including Kuki-Chin-Naga). Later during the past 2,000 years, Western Sino-Tibetan diversity in the Assam plains would have become assimilated by the expansion of Bodo-Garo.

Proto-Western Sino-Tibetan is not reconstructable, since it is a linkage rather than an actual branch. There are some lexical isoglosses that roughly distinguish Western Sino-Tibetan from Eastern Sino-Tibetan, although those are not numerous. This is similar to the satem-centum division in Indo-European that occurred as a result of horizontal rather than vertical transmission. Examples include:

WST *mik 'eye' vs. EST *myak 'eye'

WST *krut 'hand' < EST word for 'fist'

The following map shows the geographic division between WST and EST, with the Eastern Himalayas forming a natural geographic barrier against the two. Lexical isoglosses for 'eye' are shown as an example.

The first person singular pronoun *kyi is also found in many WST branches, including Newaric, Tshangla, Gongduk, West Himalayish, and Miju. It is also found in Kusunda and Basum.

Other widespread WST forms include:

*kwi 'dog'

*srik 'louse'

*krVŋ 'wing'

*li 'seed'

*-ruul 'snake'

*(b)wa 'bird'

**ku(oi) 'bee'

The forms above are also attested in EST languages, but very few EST branches have them, and the ones that do have many more variations of these forms. On the other hand, these forms are more consistent in WST languages. Thus, this points to a diffusion of a linkage of WST languages that had originated from the EST area. In Insular Southeast Asia, a similar parallel would be the relationship of Malayo-Polynesian to Formosan languages.

Sources

Gerber, Pascal. 2018. Areal features in Gongduk, Bjokapakha and Black Mountain Mönpa phonology. Unpublished draft.

Hale, Austin. 1973. Clause, sentence, and discourse patterns in selected languages of Nepal IV: word lists. (Summer Institute of Linguistics Publications in Linguistics and Related Fields 40). Kathmandu, Nepal: Summer Institute of Linguistics and Tribhuvan University Press.

DeLancey, Scott. 2015. "Morphological Evidence for a Central Branch of Trans-Himalayan (Sino-Tibetan)." Cahiers de linguistique - Asie oriental 44(2):122-149. December 2015. doi:10.1163/19606028-00442p02