From transitive to intransitive and voiceless to voiced in Proto-Sino-Tibetan

Abstract This paper offers new evidence from Stau, Geshiza, and Khroskyabs to address the question of directionality in valency-changing derivations Sino-Tibetan. Examining causative anticausative verb stem pairs adds that Proto-Sino-Tibetan, a number intransitive stems are derived transitive stems, some cases as result * N ‑ prefixation, other voicing alternation independent prefixation. In addition, proto-sigmatic prefix (* s -) does not cause devoicing Khroskyabs, but rather often undergoes assimilation, has more than just causativization function. Furthermore, by looking at Gyalrong, Minyag, Tangut, Middle Chinese, Old Chinese we emphasize there is no synchronic support induced ‑, nor historical claim caused Proto-Gyalrongic, or even genetically deeper stages.