Ethnic groups in the Soviet Union

thumb|right|250px|Minsk, Belarus, 2011: old street sign in Belarusian (right) replaced with new one in Russian (left). Russification (), Russianisation or Russianization, is a form of cultural assimilation in which non-Russians adopt Russian culture and Russian language either voluntarily or as a result of a deliberate state policy.

De-Cossackization (; ) was the Bolshevik policy of systematic repression against the Cossacks in territories of the former Russian Empire between 1919 and 1933, especially the Don and Kuban Cossacks in Russia, aimed at the elimination of the Cossacks as a distinct collectivity by exterminating the Cossack élite, coercing all other Cossacks into compliance, and eliminating Cossack distinctness. Several scholars have categorised this as a form of genocide, whilst other historians have highly disputed this classification due to the contentious figures involved, which range from "a few thousand to

mass population transfers, 1939 to 1941