The argument is based on the discovery of cognates with Qiangic languages, that are superficially undetectable due to the high degree of phonological erosion of the Naic languages, but can be uncovered through a systematic examination of lexical correspondences. Progress in the reconstruction of rGyalrongic languages and other languages of the Qiangic branch offers an improved basis for reconstruction. For instance, it appears that Proto-Naish *-o corresponds both to Proto-Rgyalrong *-o and *-aŋ, suggesting a merger between a closed syllable and an open syllable.
Chirkova (2012)[3] confirms that "Shixing displays significant similarity with Na [i.e. Naish] languages in all its linguistic subsystems and no comparable similarity with any other local language or group of languages" (p. 154). From a detailed comparison, the author concludes that "Shixing can be hypothesized to be a Na language that has undergone considerable restructuring" (p. 157).
Lidz (2010)
Lidz (2010)[4] groups the Naxi varieties as follows, but does not consider where these languages fit within Sino-Tibetan. Lidz notes that the western groups call themselves "Naxi", whereas the eastern groups call themselves "Na" — hence the parentheses. Lidz (2010) also notes that the Na (Eastern) speakers of Sichuan are officially classified as ethnic Mongols by the Chinese government. Namuyi and Shixing are not addressed.
^Lama, Ziwo Qiu-Fuyuan. 2012. Subgrouping Of Nisoic (Yi) Languages: A Study From The Perspectives Of Shared Innovation And Phylogenetic Estimation. Ph.D. dissertation, University of Texas at Arlington.
