Shah Ismail, the founder of the Safavid dynasty, who established Twelver Shia Islam as the official religion of Iran at the beginning of the sixteenth century, was revered by his followers as a Sufi master. Sufism, or Islamic mysticism, has a long tradition in Iran. It developed there and in other areas of the Islamic empire during the ninth century among Muslims who believed that worldly pleasures distracted from true concern with the salvation of the soul. Sufis generally renounced materialism, which they believed supported and perpetuated political tyranny. Their name is derived from the Arabic word for wool, suf, and was applied to the early Sufis because of their habit of wearing rough wool next to their skin as a symbol of their asceticism. Over time a great variety of Sufi brotherhoods was formed, including several that were militaristic, such as the Safavid order, of which Ismail was the leader.

Although Sufis were associated with the early spread of Shia ideas in the country, once the Shia clergy had consolidated their authority over religion by the early seventeenth century, they tended to regard Sufis as deviant. At various periods during the past three centuries some Shia clergy have encouraged persecution of Sufis, but Sufi orders have continued to exist in Iran. During the Pahlavi period, some Sufi brotherhoods were revitalized. Some members of the secularized middle class were especially attracted to them, but the orders appear to have had little following among the lower classes. The largest Sufi order was the Nimatollahi, which had khanehgahs, or teaching centers, in several cities and even established new centers in foreign countries. Other important orders were the Dhahabi and Kharksar brotherhoods. Sufi brotherhoods such as the Naqshbandi and the Qadiri also existed among Sunni Muslims in Kordestan. There is no evidence of persecution of Sufis under the Republic, but the brotherhoods are regarded suspiciously and generally have kept a low profile.

Iran also contains Shia sects that many of the Twelver Shia clergy regard as heretical. One of these is the Ismaili, a sect that has several thousand adherents living primarily in northeastern Iran. The Ismailis, of whom there were once several different sects, trace their origins to the son of Ismail who predeceased his father, the Sixth Imam. The Ismailis were very numerous and active in Iran from the eleventh to the thirteenth century they are known in history as the "Assassins" because of their practice of killing political opponents. The Mongols destroyed their center at Alamut in the Alborz Mountains in 1256. Subsequently, their living imams went into hiding from non-Ismailis. In the nineteenth century, their leader emerged in public as the Agha Khan and fled to British-controlled India, where he supervised the revitalization of the sect. The majority of the several million Ismailis in the 1980s live outside Iran.

Another Shia sect is the Ahl-e Haqq. Its adherents are concentrated in Lorestan, but small communities also are found in Kordestan and Mazandaran. The origi22c gins of the Ahl-e Haqq are believed to lie in one of the medieval politicized Sufi orders. The group has been persecuted sporadically by orthodox Shias. After the Revolution, some of the sect's leaders were imprisoned on the ground of religious deviance.

Data as of December 1987