Musta'li Ismailism

Musta'li Isma'ilism (Arabic: المستعلية, romanized: al-Mustaʿliyya) is a branch of Isma'ilism named for their acceptance of al-Musta'li as the legitimate ninth Fatimid caliph and legitimate successor to his father, al-Mustansir Billah (r.1036–1094/1095). The Nizari the other living branch of Ismailism, led by Aga Khan V believe the ninth caliph was al-Musta'li's elder brother, Nizar.

The Musta'li originated in Fatimid-ruled Egypt, later moved its religious center to Yemen, and gained a foothold in 11th-century Western India through missionaries.