Islamic movement that split from the Twelver Shiʿa over the successor of the sixth imam, Jaʿfar al-Sadiq (d. 765).
Some believed that Jaʿfar had appointed his son, Ismaʿil as his successor, but Ismaʿil predeceased Jaʿfar, thus making his brother, Musa, their father's successor. Supporters of Ismaʿil, however, maintained that his son, Muhammad, should become imam.
The Ismaʿili movement, whose followers are generally known as seveners of Ismaʿilis, spawned several subdivisions, including the Fatimids, the Assassins, the Tayyibis, and the Nizaris. The Fatimids developed from a group of Ismaʿilis who had maintained their movement in secret from the time of Jaʿfar's death until about the mid-ninth century. This group believed that Ismaʿil had not really died but had gone into occlusion, and that Muhammad, the seventh imam, would reappear as the Mahdi. The Fatimids founded Cairo in 969 c.e. and were wiped out in 1021 after their sixth caliph, al-Hakim, died. Al-Hakim's followers consolidated in the mountains of Syria and are known as Druze.
Outside Egypt, the Ismaʿili movement was propagated by Hasan-i-Sabbah, from his mountain fortress of Alamut in northern Iran in 1090 c.e. The movement he founded was known as the Assassins because of their use of hashish (users of hashish are called hashshashin in Arabic. Hasan's followers were notorious for murdering their enemies as a form of intimidation, from whence assassin was coined. After Hasan's death, the followers of the movement came to be known as Nizari Ismaʿilis, named for Nizar, an heir to the Fatimid caliphate whose claim was usurped in a palace coup, and whose namesake succeeded Hasan, claiming descent from the Fatimid Nizar. The Nizar Ismaʿili rule at Alamut ended with the Mongol conquest of 1256. Survivors kept the movement alive, however, settling in Azerbaijan and India. In 1840, their imam took the title Agha Khan, which continues until today. His followers, known as Khojas, are located mainly in Gujarat, Bombay, and East Africa, with others scattered around the world, including a small group based at Salamiyya, Syria.
see also druze; mahdi; shiʿism.