Where does “བཞི་བཅུ” come from?

བཞི་བཅུ (Tibetan) comes from Tibetan བཅུ, from Proto-Sino-Tibetan ts(j)i(j) ~ tsjaj — ten.

བཞི་བཅུ (Tibetan): forty

Definitions

Step	Language	Word	Meaning
1	Tibetan	བཅུ	ten; future of འཆུ
2	Proto-Sino-Tibetan	ts(j)i(j) ~ tsjaj	ten

བཞི་བཅུ — Etymology, Origin & Word History | Etymology Explorer