The Fatimids arrived to power in Ifriqiya in 909, when they overthrew the reigning Aghlabid dynasty with the support of the Kutama Berbers. In contrast to their predecessors, who were content to remain a regional dynasty in the western fringes of the Abbasid Caliphate, the Fatimids held ecumenical pretensions: as an Isma'ili Shi'a sect claiming descent from Fatima, the daughter of Muhammad and wife of Ali, they regarded the Sunni Abbasids as usurpers and were determined to overthrow them and take their place. Thus in early 910 the Fatimid ruler Ubayd Allah declared himself imam and caliph as "al-Mahdi Billah" (r. 909–934).[1]