The Decline of the Central Government

The very processes that led to the rise of the early Islamic empire, its elites, and its cultural forms resulted in its collapse and transformation. The decline of the ʿAbbasid Empire began even in the midst of consolidation. While the regime was strengthening its military and administrative institutions and encouraging a flourishing economy and culture, other forces were set in motion that would eventually unravel the ʿAbbasid Empire.

As early as Harun al-Rashid's reign (786–809), the problems of succession had become critical. Harun bequeathed the caliphate to his elder son, al-Amin, and the governorship of Khurasan and the right to succeed his brother to his younger son, al-Maʾmun. The independence of Khurasan under al-Maʾmun was probably set up by Harun to satisfy the demands of the eastern Iranian warlords. With the death of Harun, al-Amin attempted to displace his brother in favor of his own son. Civil war resulted. Al-Amin was backed by the Baghdadi population (the abnaʾ). These forces may have included the descendants of the original ʿAbbasid forces from Khurasan but most likely were forces rallied for the civil war on the basis of royal patronage and not on any abiding ethnic or historical loyalty. Al-Maʾmun turned to Arab forces in Khurasan and to the independent Khurasanian warlords. In a bitter civil war, al-Maʾmun defeated his brother and in 813 assumed the caliphate. With Maʾmun's conquest of Baghdad, the empire was dominated by Khurasanians.