Approaching the historical phonology of three highly eroded Sino-Tibetan languages

Naxi, Na and Laze are three languages whose position within Sino-Tibetan is controversial. We propose that they are descended from a common ancestor (‘Proto-Naish’). Unlike conservative languages of the family, such as Rgyalrong and Tibetan, which have consonant clusters and final consonants, Naxi, Na and Laze share a simple syllabic structure (consonant+glide+vowel+tone) due to phonological erosion. This raises the issue of how the regular phonological correspondences between these three languages should be interpreted, and what phonological structure should be reconstructed for Proto-Naish. The regularities revealed by comparing the three languages are interpreted in light of potential cognates in conservative languages. This brings out numerous cases of phonetic conditioning of vowels by place of articulation of a preceding consonant or consonant cluster. Overall, these findings warrant a relatively optimistic conclusion concerning the feasibility of unraveling the phonological history of highly eroded language subgroups within Sino-Tibetan.