Abd Allah al-Mahdi Billah

Isma'ili Imam and first Fatimid Caliph from 909 to 934

Abū Muḥammad ʿAbd Allāh ibn al-Ḥusayn (Arabic: أبو محمد عبد الله بن الحسين; 31 July 874 – 4 March 934), better known by his regnal name al-Mahdī biʾllāh (Arabic: المهدي بالله, "The Rightly Guided by God"), was the founder of the Isma'ili Fatimid Caliphate, the only major Shi'a caliphate in Islamic history, and the eleventh Imam of the Isma'ili branch of Shi'ism. He was born as Saʿīd ibn al-Ḥusayn (سعيد بن الحسين) in Askar Mukram to a family that led the secret Isma'ili missionary network (da'wa), propagating on behalf of the hidden imam, Muhammad ibn Isma'il, who would return as the prophesied Islamic messiah (mahdi). Orphaned at a young age, he moved to Salamiya, the family's base of operations, where he was adopted by his uncle.

From Wikipedia, under CC BY-SA. More on occurri.