Where does “בעלאַרוס” come from?

בעלאַרוס (Yiddish) comes from Belarusian Белару́сь, from Old East Slavic Бѣла Русь — {{w|White Ruthenia}} or White Rus.

Ancestry of “בעלאַרוס”, step by step

StepLanguageWordMeaning
1BelarusianБелару́сь—
2Old East SlavicБѣла Русь{{w|White Ruthenia}} or White Rus
Every word from Old East Slavic Бѣла Русь →Every word from Belarusian Белару́сь →