FATIMITES, also called FATIMIDES, the name of a dynasty called of ter Fatima, daughter of the prophet Mohammed, from whom and her husband the Caliph Ali, son of Abu Talib, they claimed descent. The dynasty is also called `Obaidi (Ubaidi) after 'Obaidallah, the first sovereign, and 'Alawi, a title which it shares with other dynasties claiming the same ancestry. Three sovereigns, who reigned in north-western Africa before the an nexation of Egypt, are worthy of mention: al-Mandi 'Obaidallah (9o9) ; al-Qa'im Mohammed 322 (934) ; al-Mansur Ismail 334 (945) The dynasty owed its rise to the attachment to the family of the prophet which was widespread in the Muslim world, and the belief that the sovereignty was the right of one of its members. Owing, however, to the absence of the principle of primogeniture there was difference of opinion as to the person whose claim should be enforced, and a number of sects arose maintaining the rights of different branches of the family. The Fatimites were supported by those who regarded the sovereignty as vested in Ismail, son of Ja`far al-Sadiq, great-great-grandson of Ali, through his second son Hosain (Husain). Of this Ismail the first Fatimite caliph was supposed to be the great-grandson. The line of ancestors between him and Ismail is, however, variously given, even his father's name being quite uncertain, and in some of the pedigrees even Ismail does not figure.
Apparently when the family first became of political importance their Alid descent was not disputed at Baghdad, and the poet al-Sharif al-Radi (d. A.H. 406: A.D. 1015), in whose family the office of Naqib (registrar of the Alids) was hereditary, appears to have acknowledged it (Diwan, ed. Beirut, p. 972). When their success became a menace to the caliphs of Baghdad, genealogists were employed to demonstrate the falsity of the claim, and a con siderable literature, both official and unofficial, rose in conse quence. The founder of the dynasty was made out to be a scion of a family of heretics from whom the terrible Carmathian sect had originated: later on (perhaps owing to the role played by Jacob, son of Killis, in bringing the Fatimites to Egypt), the founder was made out to have been a Jew, either as having been adopted by the heretic supposed to be his father, or as having been made to personate the real 'Obaidallah, who had been killed in captivity.
At some time after his first successes al-Shi`i sent a messenger (apparently his brother) to the head of his sect at Salamia, bid ding him come to the Kutama country, and place himself at the head of affairs, since al-Shi'i's followers had been taught to pay homage to a Mandi who would at some time be shown them. It is said that 'Obaidallab, who now held this post, was known to the court at Baghdad, and that on the news of his departure orders were sent to the governor of Egypt to arrest him : but by skilful simulation 'Obaidallah succeeded in escaping this danger and with his escort reached Tripoli safely. Instructions had by this time reached the Aghlabite Ziyadatallah to be on the watch for the Mandi, who was finally arrested at Sijilmasa (Tafilalt) in the year A.H. 292 (A.D. 905) ; his companion, al-Shi`i's brother, had been arrested at an earlier point, and the Mandi's journey to the south-west must have been to elude pursuit.