Al-Ma'mun

Al-Ma'mun, born Abdallah in Baghdad in September 786, was the seventh Abbasid caliph, ruling from 813 to 833. His reign saw the Abbasid Caliphate at a peak of power and prosperity. He is remembered as a key figure of the Islamic Golden Age for championing the Graeco-Arabic translation movement, fostering learning and science in Baghdad, and sponsoring the publication of al-Khwarizmi's work on algebra. He also strongly supported Mu'tazilism, a rationalist school of Islamic theology.

He came to power after a civil war against his half-brother al-Amin, and much of his rule involved peace campaigns. His backing of Mu'tazilism led to the imprisonment of the Sunni scholar Ahmad ibn Hanbal in an episode called the mihna. In foreign policy, he maintained both war and diplomacy with the Byzantine Empire, with the balance shifting during his military campaigns.

Birth and education

Abdallah was born on the same night his uncle al-Hadi died and his father, Harun al-Rashid, became caliph—a night later called the "night of the three caliphs." His mother, a concubine named Marajil from Badghis, died soon after, and he was raised by Harun's wife Zubayda, a granddaughter of Caliph al-Mansur. As a young prince, he studied classical Arabic with al-Kisa'i, adab with Abu Muhammad al-Yazidi, and received training in music and poetry. He excelled in Hanafi fiqh under al-Hasan al-Lu'lu'i and became an active transmitter of hadith. Described as the most intellectual Abbasid caliph, his love of knowledge shaped his rule.

Appointment as successor and Governor of Khurasan

Despite being the eldest son, in 794 Harun named the second-born Muhammad (al-Amin) as first heir, due to family pressure and Muhammad's higher birth as a descendant of Abbasids on both sides. Abdallah became second heir in 799 under the name al-Ma'mun, with the Barmakid Ja'far ibn Yahya as his guardian. A third heir, al-Qasim (al-Mu'tamin), was also appointed. These arrangements were publicly confirmed in 802 during a pilgrimage to Mecca: al-Amin would succeed in Baghdad, while al-Ma'mun would remain his heir and rule an enlarged Khurasan.

This was significant because Khurasan was the birthplace of the Abbasid Revolution and a source of military and administrative elites. The large Iranian presence in the state, exemplified by the Barmakids, likely influenced al-Ma'mun's appointment, given his mother's eastern Iranian origins. The agreement gave his viceroyalty extensive autonomy, though modern historians suspect later accounts were distorted in his favor. Al-Mu'tamin received frontier areas with Byzantium.

Rivalry between the brothers surfaced quickly. In 803, the Barmakids fell from power, possibly because they had grown too powerful, but also because al-Amin sided with the abnaʾ elite and al-Ma'mun with the Barmakids, making their removal necessary for al-Amin's succession.

Al-Fadl ibn Sahl, an Iranian whose father had converted to Islam and served the Barmakids, replaced Ja'far as al-Ma'mun's tutor, and by 806 became his secretary, marking him as a future vizier. In 804, al-Ma'mun married his cousin Umm Isa, daughter of Caliph al-Hadi, and they had two sons, Muhammad al-Asghar and Abdallah. After the Barmakids' fall, the administration became more centralized, and the influence of the abnaʾ grew, with many sent to provincial posts.