Muhammad, the future al-Amin, was born in April 787 to the
Abbasid caliph
Harun al-Rashid () and
Zubayda, herself descended from the second Abbasid caliph,
al-Mansur (). Muhammad had an elder half-brother, Abdallah, the future
al-Ma'mun (), who had been born in September 786. However, Abdallah's mother was a Persian slave concubine, and his pure Abbasid lineage gave Muhammad seniority over his half-brother. Indeed, he was the only Abbasid caliph to claim such descent. Already in 792, Harun had Muhammad receive the oath of allegiance (''
bay'ah) with the name of al-Amīn
("The Trustworthy"), effectively marking him out as his main heir, while Abdallah was not named second heir, under the name al-Maʾmūn'' ("The Trusted One") until 799. Both brothers were assigned members of the powerful
Barmakid family as tutors: al-Amin's tutor was
al-Fadl ibn Yahya, while al-Ma'mun's was
Ja'far ibn Yahya. of
Harun minted in
Baghdad 184
AH (800 CE) with the name of
Commander of the Faithful Harun al-Rashid and his first
Heir, prince al-Amin These arrangements were confirmed and publicly proclaimed in 802, when Harun and the most powerful officials of the Abbasid government made the
pilgrimage to
Mecca. Al-Amin would succeed Harun in
Baghdad, but al-Ma'mun would remain al-Amin's heir and would additionally rule over an enlarged
Khurasan. This was an appointment of particular significance, as Khurasan had been the starting-point of the
Abbasid Revolution which brought the Abbasids to power, and retained a privileged position among the Caliphate's provinces. Furthermore, the Abbasid dynasty relied heavily on Khurasanis as military leaders and administrators. Many of the original Khurasani Arab army (
Khurasaniyya) that came west with the Abbasids were given estates in
Iraq and the new Abbasid capital, Baghdad, and became an elite group known as the
abnāʾ al-dawla ("sons of the state/dynasty"). This large-scale presence of an
Iranian element in the highest circles of the Abbasid state, with the Barmakid family as its most notable representatives, was certainly a factor in the appointment of al-Ma'mun, linked through his mother with the eastern Iranian provinces, as heir and governor of Khurasan. The stipulations of the agreement, which were recorded in detail by the historian
al-Tabari, accorded al-Mamun's Khurasani viceroyalty extensive autonomy. However, modern historians consider that these accounts may have been distorted by later apologists of al-Ma'mun in the latter's favour. Harun's third heir, al-Mu'tamin, received responsibility over the
frontier areas with the
Byzantine Empire in
Upper Mesopotamia and
Syria. n coinage, naming al-Amin as governor of Khurasan, These complex arrangements, sealed with mutual judicial and religious oaths, clearly demonstrate that Harun was conscious of their precariousness, in view of the profound differences between al-Amin and al-Ma'mun, both in character and in interests. Very quickly, this latent rivalry had important repercussions: almost immediately after the court returned to Baghdad in January 803, the Abbasid elites were shaken by the abrupt fall of the Barmakid family from power. On the one hand, this event may reflect the fact that the Barmakids had become indeed too powerful for the Caliph's liking, but its timing suggests that it was tied to the succession issue as well: with al-Amin siding with the
abnāʾ and al-Ma'mun with the Barmakids, and the two camps becoming more estranged every day, if al-Amin was to have a chance to succeed, the power of the Barmakids had to be broken. Indeed, the years after the fall of the Barmakids saw an increasing centralization of the administration and the concomitant rise of the influence of the
abnāʾ, many of whom were now dispatched to take up positions as provincial governors and bring these provinces under closer control from Baghdad. This led to unrest in the provinces, especially Khurasan, where local elites had a long-standing rivalry with the
abnāʾ and their tendency to control of the province (and its revenues) from Iraq. The harsh taxation imposed by a prominent member of the
abnāʾ,
Ali ibn Isa ibn Mahan, even led to a revolt under
Rafi ibn al-Layth, which eventually forced Harun himself, accompanied by al-Ma'mun and the powerful chamberlain (
hajib) and chief minister
al-Fadl ibn al-Rabi, to travel to the province in 808. Al-Ma'mun was sent ahead with part of the army to
Marv, while Harun stayed at
Tus, where he died on 24 March 809. ==Caliphate==