Abu al-Ala Idris al-Mamun (Arabic: أبو العلا المأمون إدريس بن المنصور; Abū Al-`lā Al-Mā'mūn Idrīs ibn Al-Manṣūr; died 16 or 17 October 1232) was an Almohad rival caliph who reigned in part of the empire from 1227 until his death.
At the death of his brother Abdallah al-Adil, a civil war broke out between Idris and Yahya al-Mutasim, who had the support of the capital Marrakech. Idris asked the Christian king Ferdinand III of Castile for help, receiving 12,000 knights who allowed him to conquer that city and to massacre the sheikhs that had supported Yahya.
Idris abandoned the Mahdi doctrine, in favour of the Sunni one. Due to his incapability to pay Ferdinand, he accepted the construction of a Christian church in Marrakech in 1230, which was anyway destroyed two years later. The side changes of Idris soon lost him popular consent. In the early 1232, when he was besieging Ceuta, Yahya took the occasion to capture Marrakech. Idris died during the march to reach the city, and was succeeded by his son Abd al-Wahid II.
| Preceded by Abdallah al-Adil |
Almohad dynasty 1227–1232 |
Succeeded by Abd al-Wahid II |