Wikipedia
Al-Mustansir, more fully al-Mustansir billah ("he who seeks victory in God"), is a Muslim regnal surname and may refer to:
- Ma'ad al-Mustansir Billah (1029–1094), eighth Fatimid Caliph
- Sayf al-Dawla ibn Hud al-Mustansir (r. 1145–1146), Muslim ruler of Valencia and Murcia
- Al-Mustansir (Baghdad) (المستنصر بالله) (died 1242), penultimate Abbasid Caliph in Baghdad from 1226 to 1242
- Al-Mustansir (Cairo), first Caliph in Cairo for the Mamluk Sultans between 1261 and 1262
- Muhammad I al-Mustansir (r. 1249-1277), Hafsid ruler of North Africa and self-declared Caliph
Al-Mustansir was a member of the Abbasid house who, following the sack of Baghdad by the Mongols in 1258, was installed as Caliph in Cairo, Egypt by the Mamluk Sultans in 1261. He was sent with an army east to recover Baghdad, but was killed in a Mongol ambush in 1261, and was succeeded by his kinsman (and rival caliph, having been proclaimed by the ruler of Aleppo) Al-Hakim I. The line of Cairo caliphs he founded lasted until the Ottoman conquest of Egypt in 1517, but they were little more than religious figureheads for the Mamluks.
Al-Mustansir Bi'llah (full name:Abû Ja`far al-Mustansir bi-llah al-Mansûr ben az-Zâhir Surname Al-Mustansir) was born in Baghdad on 1192. On his father's death in 1226 he has succeeded his father Az-Zahir as the thirty-sixth Abbasid Caliph. Al-Mustansir died on 5 December 1242. His son Al-Musta'sim succeeded him as the caliph.
Mustansiriya Madrasah, was established in 1227 (or 1232/34 A.D. by some accounts) by the Abbasid Caliph Al-Mustansir and was one of the oldest universities in the world. Its building, located on the left bank of the Tigris River, survived the Mongol invasion and has been restored.