notable Muslim minorities include Moscow, Saint Petersburg, the republics of Adygea, North Ossetia-Alania and Astrakhan, Moscow, Orenburg and Ulyanovsk oblasts. There are over 5,000 registered religious Muslim organizations, equivalent to over one sixth of the number of registered Russian Orthodox religious organizations of about 29,268 as of December 2006. History In the mid-7th century AD, as part of the Muslim conquest of Persia, Islam was introduced to the Caucasus region, parts of which were later permanently incorporated by Russia. The first people to become Muslims within current Russian territory, the Dagestani people (region of Derbent), converted after the Arab conquest of the region in the 8th century. The first Muslim state in the future Russian lands was Volga Bulgaria (922). The Tatars of the Khanate of Kazan inherited the population of believers from that state. Later most of the European and Caucasian Turkic peoples also became followers of Islam. The Tatars of the Crimean Khanate, the last remaining successor to the Golden Horde, continued to raid Southern Russia and burnt down parts of Moscow in 1571. Until the late 18th century, the Crimean Tatars maintained a massive slave-trade with the Ottoman Empire and the Middle East, exporting about 2 million slaves from Russia and Ukraine over the period 1500–1700. From the early 16th century up to including the 19th century, all of Transcaucasia and southern Dagestan was ruled by various successive Iranian empires (the Safavids, Afsharids, and the Qajars), and their geopolitical and ideological neighboring arch-rivals, on the other hand, the Ottoman Turks. In the respective areas they ruled, in both the North Caucasus and South Caucasus, Shia Islam and Sunni Islam spread, resulting in a fast and steady conversion of many more ethnic Caucasian peoples in adjacent territories. The period from the Russian conquest of Kazan in 1552 by Ivan the Terrible to the ascension of Catherine the Great in 1762 featured systematic Russian repression of Muslims through policies of exclusion and discrimination - as well as the destruction of Muslim culture by the elimination of outward manifestations of Islam such as mosques. The Russians initially demonstrated a willingness in allowing Islam to flourish as Muslim clerics were invited into the various regions to preach to the Muslims, particularly the Kazakhs, whom the Russians viewed with contempt. However, Russian policy shifted toward weakening Islam by introducing pre-Islamic elements of collective consciousness. Such attempts included methods of eulogizing pre-Islamic historical