The Abbasid Caliphate was the third of the Islamic caliphates. It was ruled by the Abbasid dynasty of caliphs, who built their capital in Baghdad after overthrowing the Umayyad caliphate from all but the al-Andalus region. Approx 6th - 8th century. AD
The Abbasids began to lose their power over the Muslim Empire before the start of the middle of the ninth century. Peasants started to revolt and slavery levels rose. In the thirteenth century, Mongolian invaders weakened the Abbasid Empire even more. Although the politics of the Empire were declining vastly, the civilization of Islam was reaching new high points and expanding greatly.
Islamic - Abbasid Caliphate: Harun al-Rashid ( the legendary caliph of 1001 Nights ), A.D. 786-809, AV dinar, AH184, citing Ja'far