Where does “Biélorussie” come from?

Biélorussie (French) comes from Italian Bielorussia, from Russian Белору́ссия, from Old East Slavic Бѣла Русь — {{w|White Ruthenia}} or White Rus.

Ancestry of “Biélorussie”, step by step

Step	Language	Word	Meaning
1	Italian	Bielorussia	—
2	Russian	Белору́ссия	—
3	Old East Slavic	Бѣла Русь	{{w\|White Ruthenia}} or White Rus

Biélorussie — Etymology, Origin & Word History | Etymology Explorer