The decline of the Arab Empire began in the 8th century, with the end of the Umayyad dynasty in 750. The Abbasids, who succeeded the Umayyads, were able to maintain the empire for several centuries, but it began to decline again in the 11th century, due to internal strife and external pressures from the Byzantines, Seljuks, and Mongols. The final blow came in 1258, when the Mongols sacked Baghdad, ending the Abbasid dynasty and effectively marking the end of the Arab Empire.