Where does “Мьянма” come from?

Мьянма (Russian) comes from Burmese မြန်မာ — Myanmar; Burma; Burmese; Myanmar.

Ancestry of “Мьянма”, step by step

Step	Language	Word	Meaning
1	Burmese	မြန်မာ	Myanmar; Burma; Burmese; Myanmar

Мьянма — Etymology, Origin & Word History | Etymology Explorer