But, the practices of old Russia obviously did not disappear overnight. The Russian-Ukrainian national experiences did not embrace racism and genocide on the British, Spanish, or American model, but discrimination directed against minority peoples - Tatars and other orientals, Turkic peoples, Jews - stained the record of the East Slavs, and black visitors inevitably felt its blows. Because the communists usually suppressed news of racial incidents, however, we have little information on the subject.Obviously the racism of Tsarist Russia continued in the USSR and became institutionalized in the form of the internal passport and definition of natsional'nost solely along lines of biological descent. This point about the racialization of Soviet categories has been noted by Russian anthropologist Marina Mogil'ner and vehemently denied by US scholars seeking to defend the Soviet dictatorship under Stalin from the charge of racial discrimination.
Source: Woodford McClellen, "Africans and Black American in the Comintern Schools, 1925-1934," The International Journal of African Historical Studies, Vol. 26, No. 2 (1993), p. 376.