Zanj Rebellion
His reign marks the apogee of the decline of the Caliphate's central authority, and the climax of centrifugal tendencies, expressed through the emergence of the autonomous dynasties of the Tulunids in Egypt and the Saffarids in the East, Alid uprisings in Hejaz and Tabaristan, and the first stirrings of the great Zanj Rebellion in lower Iraq.