 Complete the following phrase:  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 Stalins 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 