The Abbasid Dynasty was the third dynasty led by caliphs in order to rule the Arabs, and was built by a descendent of Muhammad's uncle. They overthrew the Umayyads, and even though they were victorious, they were still overthrown by the Mamluks, a Turkish army.

The 'Abassid caliphate (758-1258) was founded on two disaffected Islamic populations: non-Arabic Muslims and Shi'ites. For the most part, the Islamic impetus to the Abassid revolution lay in the secularism of the Umayyad caliphs. The Umayyads had always been outsiders—as a wealthy clan in Mecca, they had opposed Muhammad—and the secularism and sometime degeneracy that accompanied their caliphate delegitimized their rule for many devout Muslims. Abbasid Caliph!

The Abassids took their name from al-'Abbas, a paternal uncle of Muhammad and early supporter of the Prophet. Their close kinship to Muhammad and the position of al-'Abbas as a Companion of the Prophet served them well in gaining support. As early as 718 AD, during the reign of Umar II, Muhammad ibn 'Ali, a great-grandson of al-'Abbas, began to proselytize in Persia to rally support for returning the caliphate to the family of the Prophet, the Hashimites.

What made the 'Abassid seizure of the caliphate unique was the heavy reliance on client Muslims, or mawali. The mawali were foreigners who had converted to Islam; because, however, they were foreigners they could not be incorporated into the kinship-based society of Arabs. They had to be voluntarily included into the protection of a clan, that is, they had to become "clients" of the clan (which is what the word mawali means). For the most part, they were second-class citizens even though they were Muslims.