Tujia
Tujia is a an independent Sino-Tibetan branch consisting of two living languages, namely Northern Tujia ("Bitsi" / "Miji") and Southern Tujia ("Mongji"). It does not subgroup with any other Sino-Tibetan branch, pointing to its position as an early split from Sino-Tibetan. Its phonology and phonotactics are very similar to those of Northern Kra (Gelao and Lachi). Tujia is highly eroded, making reconstruction difficult and problematic at times. Final consonants have been lost, "prefix pre-emption" (prefix assimilation) is rampant, and various fossilized affixes have been have been added to lexical roots, making them difficult to identify. Thus, top-down reconstructions are often necessary. Northern Tujia and Southern Tujia do not always show regular correspondences.
Non-Sino-Tibetan substratum
Although the Sino-Tibetan heritage of Tujia is quite evident, there are also various words that have no Sino-Tibetan parallels. Hence, I believe Tujia contains a non-Sino-Tibetan substratum.
Blench (2009) has identified various words in Tujia as non-Sino-Tibetan agricultural terms, but some of those are in fact Sino-Tibetan roots that have been highly eroded. Blench (2009) also claims that Bai has a non-Sino-Tibetan substratum based on unique-looking agricultural terms, but most of those are in fact Sino-Tibetan words that have undergone heavy erosion.
Circumfixal negation
Tujia is notable for being the only Sino-Tibetan branch in southern China that possesses circumfixal and final negation, a linguistic feature that is also typical of Kra languages and of Yang Zhuang, pointing to contact with a now-extinct Sino-Tibetan branch, or branches in the Proto-Kra homeland in and around Guangxi. In the Sino-Tibetan phylum, these linguistic features are found in Kuki-Chin-Naga languages but not in Lolo-Burmese or Qiangic languages. However, this does mean that Tujia is closely related to Kuki-Chin-Naga or any of the Central Sino-Tibetan languages. Rather, this must have been a shared retention from an early stage of Sino-Tibetan when circumfixal negation was more common among Sino-Tibetan languages.
Lexical layers:
Isolate substratum
Eastern Sino-Tibetan independent branch
"Old Middle Yangtze" [pre-Hmong-Mien] language phylum (limited loanwords)
Burmo-Qiangic influences
Old Chinese
Southwestern Mandarin / Xiang
Reconstruction of Proto-Tujia
Background
Tujia consists of two languages (Northern Tujia and Southern Tujia) spoken in northwestern Hunan, China. So far, no reconstruction of Proto-Tujia exists. The Proto-Tujia reconstructions below are based from Northern Tujia and Southern Tujia forms given in Tian & He (1986).
Due to the heavily eroded lexical forms in synchronic Tujia languages, Proto-Tujia is not easy to reconstruct. In Tujia lects, prefixes (some of which are frozen classifiers) and suffixes were often added to the original noun stem over time, often making it difficult to determine which syllable to reconstruct.
Although the Automated Similarity Judgment Program (ASJP) classifies Tujia outside the main Sino-Tibetan cluster and treats it as an isolate, I consider Tujia to be a fully Sino-Tibetan language.
In Hsiu (2015), I proposed that there is a "Plateau" linguistic area covering most of Guizhou and western Hunan. The Plateau linguistic area includes Hmongic, Northern Kra (Gelao and Lachi), Loloish, and Tujia. Phonological features found in this linguistic area include the loss of final rimes, limited number of tones (often only 4), and preference for nouns with 2-3 syllables. On the other hand, the "Lingnan" linguistic area in Guangxi and Guangdong includes Mienic, Tai, Southern Kra, and Yue Chinese, and has phonological features opposite of those found in the Plateau linguistic area.
The agricultural lexicon of Tujia mainly has parallels with Lolo-Burmese and Old Chinese, with some parallels in Proto-Hmong-Mien. Roger Blench (2009) argues that Tujia has non-Sino-Tibetan agricultural vocabulary, but Blench's proposed non-Sino-Tibetan forms in Tujia are actually mostly from Sinitic and Burmo-Qiangic; the Tujia forms have simply undergone heavy erosion.
Sound changes
Southern Tujia tends to preserve initials better, while Northern Tujia tends to preserve rimes better. Southern Tujia -o is a result of vowel backing from Proto-Tujia *-a > > -ɑ > -o. This seems to be a areal feature, as many Gelao dialects (Hongfeng, Judu, etc.) display Proto-Kra *-a > > -ɑ. Northern Tujia displays Proto-Tujia *n- > l-, Proto-Tujia *m- > p-, and Proto-Tujia initial stop devoicing / aspiration for some, but not all words.
Proto-Tujia displays some influence from Burmo-Qiangic languages, and some forms display Qiangic brightening (PTB *-a > -i). However, the majority of words have no parallels with Burmo-Qiangic. Despite the geographical proximity, there are not many parallels with Proto-Hmong-Mien. Tujia is also not "Donor-Miao-Yao," the Tibeto-Burman branch posited by Benedict (1987) that had given Proto-Hmong-Mien its numerals and various other lexical items. Tujia is thus best treated as an independent Sino-Tibetan branch.
Autonyms
The Southern Tujia autonym is "Mongji," which is reminiscent of "Hmong." Could this have been an areal endonym?
The Northern Tujia autonym is "Biji" or "Miji," which is reminiscent of "Miji" in Arunachal. "Mi" is derived from Proto-Tibeto-Burman *mi 'person'.
List of reconstructions
Note: Since final non-nasal stops cannot be reconstructed for Proto-Tujia, I have used top-down reconstruction to reconstruction likely Pre-Tujia forms.
References
Benedict, Paul K. 1987. "Early MY/TB Loan Relationships." In Linguistics of the Tibeto-Burman Area, 10 , no. 2: 12-21.
Blench, Roger. 2009. If agriculture cannot be reconstructed for Proto-Sino-Tibetan, what are the consequences?. Paper presented at the 42nd International Conference on Sino-Tibetan Language and Linguistics (ICSTLL 42), Chiang Mai, November 2-4, 2009.
Hsiu, Andrew. 2015. The linguistic geography of Southern China. Presented at HLS 21, Kathmandu, Nepal.
Tian Desheng and He Tianzhen, et al., eds. 1986. Tujiayu jianzhi [Brief description of the Tujia language]. Beijing: Nationalities Press. Accessed via STEDT database.