Where does “*ŋuːᴬ⁴” come from?

*ŋuːᴬ⁴ (Proto-Southwestern Tai) comes from Proto-Tai ŋwɯːᴬ — snake.

Ancestry of “*ŋuːᴬ⁴”, step by step

Step	Language	Word	Meaning
1	Proto-Tai	ŋwɯːᴬ	snake