Islam is the 2nd biggest religion in Russia. According to estimates there are more than 20 million Muslims, a number that has risen 40% in the last 15 years. The 1st Muslims within current Russian territory were the Dagestanis after Arab conquests in the 8th century.
The first Muslim state was Volga Bulgaria (922 CE). Later most European and Caucasian Turkic people also became Muslim. Russia added vast tracts of Muslim land to its current state beginning with the conquest of the Khanate of Kazan in 1552, which brought the Tatars into Russia. The lower Volga Muslim Astrakhan Khanate was conquered in 1556, the Siberia Khanate in the 16th century and the Crimean Khanate in 1739. In the 18th and 19th centuries, Russian conquests in North Caucasus brought Muslims of Dagestan, Chechnya, Ingushetia and others into the Russian state. The Muslim states of Central Asia and Azerbaijan were brought into Soviet Russia. The latter are now independent.
Under Communism, Islam was suppressed with Musjids being closed down and Afghanistan invaded. Recently there have been arrests and harassment by authorities, as well as confiscation of Islamic educational material. The vast majority of Muslims are Sunni. Most observers say Islam is the most rapidly growing religion in Russia. Moscow now has a Muslim population 2nd only to Istanbul among European nations. A record 18,000 Russian Muslims attended Hajj in 2006. Islamic publications exist in Russian. The Caucasus including Dagestan, Ingushetia and Chechnya have fought on and off for independence till today. Some analysts say Muslims will be in the majority in Russia by 2050.