Mansur ibn al-Mahdi (Arabic: منصور بن المهدي) was an Abbasid prince, son of Abbasid caliph al-Mahdi, brother of caliph al-Hadi and Harun al-Rashid. Mansur was governor of Syria during his nephew caliph al-Amin's reign.
Mansur was the son of al-Mahdi and his mother was al-Bahtariyah, the noble-born daughter of the Persian rebel,[1] Masmughan of Damavand,[2] against whom Mahdi was first sent to Khurasan.[1] Her mother was Bakand, the daughter of Isbahbadh, Farrukhan the Little.[3] She had a sister named Smyr.[2] She bore al-Mahdi a son named for his grandfather, Mansur, and two daughters, Sulaimah and Aliyah.[1]
His father, nominated his two elder sons; Musa al-Hadi and Harun al-Rashid as heirs. Mansur maintains good relations with all his siblings.
Mansur was appointed as governor of Syria in 809. He remained in office until al-Amin reappointed Sulayman to govern Syria around 809–810 in response to unrest in Damascus emanating from the theft of a prized crystal pitcher from the Umayyad Mosque by the incumbent governor, Sulayman's nephew Mansur. The outrage of the Damascenes prompted them to refuse prayer under Abbasid leadership.[4]
After his dismissal from the office, Mansur returned to Baghdad in 810.
Mansur was contemporary and related to several Abbasid caliphs, princes and princesses. He had total ten half-siblings and he had two full sisters named Aliyah and Sulaimah.