Kra-Dai tonogenesis in Austro-Tai perspective.

The complex tone inventories of Kra-Dai languages derive in part from earlier segmental codas via transphonologization. Comparative Austro-Tai research has identified systematic correspondences between Kra-Dai tones and Austronesian codas, but significant gaps remain: the segmental origins of tone categories *B and *C remain disputed, divergent tonal patterns among Kam-Sui languages lack explanation, and the chronology of transphonologization remains unclear. Building on Sagart's (2019) Austro-Tai model, we propose (1) that some Kam-Sui languages underwent a chain shift from Proto-Kra-Dai codas *‑χ and *‑h to *‑h and *‑ʔ, paralleling Tai developments, as a contact-induced effect, and (2) that Tai evidence suggests Proto-Austro-Tai *‑R persisted as a rhotic coda into the Proto-Tai stage. These findings imply an extended chronology of gradual transphonologization spanning centuries, enhancing our understanding of tonogenesis as long-running, areally co-influencing processes in East and Southeast Asian languages while strengthening empirical support for the Austro-Tai hypothesis. [ABSTRACT FROM AUTHOR]