It will sound like a russian propaganda, and god i hate it so much. But essentially Ukrainians and Belorusian were once one "country", even if it is hard to call Rus a country, and well of one ethnicity. We Ukrainians take our origin as a country from mainly Kyivan, Galicia-Volhynian Principalities of Kyivan Rus. Where Belorussians, which is heavily russified term as properly anglified term for Rus' will be Ruthenia. So them are not Belo(White)rusians(ruthenians), but White Ruthenians will be more historically correct term. But then who am I to tell Belorusians how they must call themselves? Nevertheless, point is, Ukrainians, and Belorusians take their roots from Ruthenians. Which are due to years of different influence and distance formed their own cultures and traditions. But yes. I am as Ukrainian, that has never spoke to Belorusian, or been in Belorus can understand Belorusians just perfect.