 Complete the following phrase:  Crimea was historically under the control of the Russian Empire from 1783 to 1917 and Soviet Union from 1918 to 1991. Following the Russian Revolution of 1917 and the Russian Civil War 7 November 1917  25 October 1922, it was established in 1921 as the Crimean Autonomous Soviet Socialist Republic within the Russian Soviet Federative Socialist Republic in the USSR. During World War II, Crimea was downgraded to the Crimean Oblast after its entire indigenous population, the Crimean Tatars were 