onwards. The Safavids made Shia Islam the official state religion in the early-16th century and aggressively proselytized the faith by forced conversion. It is believed that by the mid-17th century most people in Iran, Iraq and the territory of the contemporary neighbouring Republic of Azerbaijan had become Shia from Sunni, an affiliation that has continued. Over the following centuries, with the state-fostered rise of an Iran-based Shia clergy, a synthesis was formed between Iranian culture and Shia Islam that marked each indelibly with the tincture of the other. History Islamic conquest of Iran Muslims conquered Iran in the time of Umar (637) and conquered it after several great battles. Yazdegerd III fled from one district to another Merv in 651. By 674, Muslims had conquered Greater Khorasan (which included modern Iranian Khorasan province and modern Afghanistan, Transoxania). As Bernard Lewis has quoted "These events have been variously seen in Iran: by some as a blessing, the advent of the true faith, the end of the age of ignorance and heathenism; by others as a humiliating national defeat, the conquest and subjugation of the country by foreign invaders. Both perceptions are of course valid, depending on one's angle of vision." Under Umar and his immediate successors, the Arab conquerors attempted to maintain their political and cultural cohesion despite the attractions of the civilizations they had conquered. The Arabs were to settle in the garrison towns rather than on scattered estates. The new non-Muslim subjects, or dhimmi, were to pay a special tax, the jizya or poll tax, which was calculated per individual at varying rates for able bodied men of military age. Iranians were among the very earliest converts to Islam, and their conversion in significant numbers began as soon as the Arab armies reached and overran the Persian plateau. Despite some resistance from elements of the Zoroastrian clergy and other ancient religions, the anti-Islamic policies of later conquerors like the Il-khanids, the impact of the Christian and secular West in modern times, and the attraction of new religious movements like Babism and the Baháʼí Faith (qq.v.), the vast majority of Iranians became and have remained Muslims. Today perhaps 98 percent of ethnic Iranians, including the population of Persia, are at least nominal Muslims. For such a fundamental, pervasive, and enduring cultural transformation, the phenomenon of Iranian conversions to Islam has received remarkably little scholarly attention. Recent research has established a