Where does “ང” come from?

ང (Tibetan) comes from Proto-Sino-Tibetan ŋa, from Proto-Sino-Tibetan l/b-ŋa — five.

ང (Tibetan): I

Definitions

Step	Language	Word	Meaning
1	Proto-Sino-Tibetan	ŋa	I
2	Proto-Sino-Tibetan	l/b-ŋa	five

ང — Etymology, Origin & Word History | Etymology Explorer