By the 1930s the mood shifted as the Soviet Union under Joseph Stalin stopped enforcing indigenization and began purging non-Russians from government and intelligentsia. Thus, a period of Russification set in. Russian became mandatory in all areas of non-Russian ethnicity and the Cyrillic script became compulsory for all languages of the Soviet Union. The constitution stated that the ASSRs had power to enforce their own policies within their territory, but in practice the ASSRs and their titular nationalities were some of the most affected by Stalin's purges and were strictly controlled by Moscow. From 1937, the "bourgeois nationalists" became the "enemy of the Russian people" and indigenization was abolished. On 22 June 1941 Germany invaded the Soviet Union, forcing it in to the Second World War, and advanced deep in to Russian territory. In response, Stalin abolished the Volga German ASSR on 7 September 1941 and exiled the Volga Germans to Central Asia and Siberia. When the Soviets gained the upper hand and began recapturing territory in 1943, many minorities of the country began to be seen as German collaborators by Stalin and were accused of treason, particularly in southern Russia. Between 1943 and 1945 ethnic Balkars, Chechens, Crimean Tatars, Ingush,