Where does “ལྔ་བཅུ” come from?

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

ལྔ་བཅུ (Tibetan): fifty

Definitions

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

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