Where does “va̋” come from?

va̋ (Zou) comes from Proto-Kuki-Chin *waa, from Proto-Sino-Tibetan *waʔ.

Ancestry of “va̋”, step by step

Step	Language	Word	Meaning
1	Proto-Kuki-Chin	*waa	—
2	Proto-Sino-Tibetan	*waʔ	—