While Proto-Sino-Tibetan is commonly considered to have two direct descendants, Proto-Sinitic and Proto-Tibeto-Burman,[2] in recent years several scholars have argued that this was not well-substantiated,[3] and have taken to calling the group "Trans-Himalayan".[4] In this case, Proto-Tibeto-Burman may be considered as equivalent to Proto-Sino-Tibetan if Sinitic is indeed not the first branch to split from Proto-Sino-Tibetan.[5]
Reconstructed features include prefixes such as the causative s-, the intransitive m-, the miscellaneous b-, d-, g-, and r-, suffixes -s, -t, and -n, and a set of conditioning factors that resulted in the development of tone in most languages of the family.[6] The existence of such elaborate system of inflectional changes in Proto-Sino-Tibetan makes the language distinctive from some of its modern descendants, such as the Sinitic languages, which have mostly or completely become analytic.
Proto-Sino-Tibetan, like Old Chinese, also included numerous consonant clusters, and was not a tonal language.
The reconstruction by Peiros & Starostin suggests a much more complex consonant inventory.[7] The phonemes in brackets are reconstructions that are considered dubious.
The consonants /ptkqʔmnŋlrj/ can take coda position, as well as the cluster /rl/. While Hill does not reconstruct /j/ as an initial consonant due to Baxter and Sagart's Old Chinese reconstruction lacking such a phoneme, he mentions that Jacques and Schuessler suggest a /j/ initial for some Old Chinese words due to potential Tibetan or Rgyalrongic cognates.[10]
Hill also claims that his reconstruction is incomplete, as it does not account for Tibetic palatalization, proto-Burmish preglottalization, Sinitic aspirates, and the Sinitic type A and B distinction of syllables.
In Gong Huangcheng's reconstruction of the Proto-Sino-Tibetan language, the finals *-p, *-t, *-k, *-m, *-n, and *-ŋ in Proto-Sino-Tibetan remained in Proto-Sinitic and Proto-Tibeto-Burman. However, in Old Chinese, the finals *-k and *-ŋ that came after the close vowel *-i- underwent an irregular change of *-k>*-t and *-ŋ >*-n. In Proto-Tibeto-Burman, *-kw and *-ŋw underwent a sound change to become *-k and *-ŋ respectively, while in Old Chinese those finals remained until Middle Chinese, where the finals underwent the same sound change.[11]
Furthermore, in Proto-Tibeto-Burman, the finals *-g, *-gw, and *-d underwent the following changes:
^Orlandi, Georg (2021). "Once again on the history and validity of the Sino-Tibetan bifurcate model". Journal of Language Relationship. 19 (4): 263–292.
^van Driem, George (2007). "The diversity of the Tibeto-Burman language family and the linguistic ancestry of Chinese". Bulletin of Chinese Linguistics. 1 (2): 211–270. doi:10.1163/2405478X-90000023.
^Peiros, Ilia; Starostin, S.A. (1996). A comparative vocabulary of five Sino-Tibetan languages. Parkville, VIC: Univ. of Melbourne, Dept. of Linguistics and Applied Linguistics. ISBN9780732513504.
^Gong Huangcheng (龔煌城) (2003). 從原始漢藏語到上古漢語以及原始藏緬語的韻母演變 [Final changes from Proto-Sino-Tibetan to Old Chinese and Proto-Tibeto-Burman] (PDF). 古今通塞:漢語的歷史與發展. 第㆔屆國際漢學會議論文集語言組 (in Chinese). pp. 187–223. Archived from the original(PDF) on 2020-11-03. Retrieved 22 October 2023.