Internecine Arab tribal rivalries, together with the…

Internecine Arab tribal rivalries, together with the bitterness of the mawali and the disaffection of the Kharijite and Shiite factions, had aid the spread of the rebellion to other parts of the Muslim empire in 749.

In this year, the Hashimiyah, aided by the western provinces, proclaim as caliph Abu al-'Abbas, a close friend of Abu Muslim.

Known subsequently as-Saffah, “the blood-shedder,” because of his savage attacks, he begins a campaign of extermination against the Umayyads, the 'Alids, other 'Abbasid leaders who have become too popular, and all other claimants to power.