Crimean Tatars, a predominantly Muslim ethnic minority who in 2001 made up 12.1% of the population, formed in Crimea in the early modern era, after the Crimean Khanate had come into existence. The Crimean Tatars were forcibly expelled to Central Asia by Joseph Stalin's government as a form of collective punishment, on the grounds that some had joined the invading Waffen-SS, forming Tatar Legions, during World War II. After the fall of the Soviet Union, Crimean Tatars began to return to the region. According to the 2001 Ukrainian population census, 58% of the population of Crimea are ethnic Russians and 24% are ethnic Ukrainians.