Abu'l-Hasan al-Hasan ibn Ali

Al-Hasan succeeded his father, Ali ibn Yahya, upon the latter's death in 1121.[1] Reduced to the coasts of modern Tunisia, during his reign, the Zirid emirate faced the increasingly threatening attacks of the Italo-Norman Kingdom of Sicily. The Normans were provoked largely by Almoravid attacks on their shores, but blamed them on the Zirids, as al-Hasan's father had requested Almoravid aid against Sicily.[1] In 1135, the Normans occupied Djerba, and finally targeted the Zirid capital of al-Mahdiya itself in 1148.[1] With his state's economy already in decline, and weakened further by drought and famine, al-Hasan was unable to resist the Norman attack, fleeing instead to the Hammadids in Algiers.[1]

There he remained under virtual house arrest until 1152, when the Almohad Caliphate under Abd al-Mu'min captured Algiers. Brought to the Almohad capital of Marrakesh, al-Hasan urged the Almohads to reconquer Ifriqiya. An Almohad expedition indeed expelled the Normans from al-Mahdiya in 1160, but al-Hasan was only allowed to settle in its extramural quarter of Zawila.[1] He remained there until the death of Abd al-Mu'min in 1167, when he was ordered to return to Marrakesh, but died on the way at Tamasna.[1]

• Tibi, Amin (2002). "Zīrids". In Bearman, P. J.; Bianquis, Th.; Bosworth, C. E.; van Donzel, E. & Heinrichs, W. P. (eds.). Encyclopaedia of Islam. Volume XI: W–Z (2nd ed.). Leiden: E. J. Brill. pp. 513–516. ISBN 978-90-04-12756-2.