Islam in the Soviet Union
Islam in the Soviet Union was the country's second-largest religion, and 90% of Muslims were adherents of Sunni Islam, with only around 10% adhering to Shia Islam. Excluding the Azerbaijan SSR, which had a Shia-majority population, all of the Muslim-majority Union Republics had Sunni-majority populations.
Source: Wikipedia — Islam in the Soviet Union (CC BY-SA 4.0)