If you recall, Muhammad had a number of uncles. Abu Talib raised him, then when Muhammad was married, he and another uncle, Abbas, each took one of Abu Talib’s younger sons to foster. Abbas’s wife became a believer very early, but Abbas fought against the Muslims at Badr. As a captive, he heard Muhammad recount a private conversation between Abbas and his wife, and this convinced him that Allah really spoke to his nephew. From that time, he became a Muslim.
While the family of Muhammad’s daughter Fatimah experienced persecution, so that they were not great in number, the family of Abbas grew and prospered. They were Quraysh but not Umayyads; their clan was the Banu Hashim. As the generations went on after the Prophet’s death, the family of Abbas reminded people that they were Hashimites, not Umayyads. They were one step closer to the Prophet in kinship and in piety.
The Abbasid family settled between Arabia and Syria, at a site now in modern Jordan. They were on a main road and could entertain visitors at their compound. This may be the link that allowed them to become close to some Arabs who had gone with the army out to the east. Now these Arabs lived in Khurasan, which meant the whole general eastern area that was most recently conquered.
The Khurasani Arabs had access to serious money. Some of the non-Arab Muslim converts who felt that the Umayyads had discriminated against them joined their Arab neighbors in dissatisfaction with Umayyad rule. In Khurasan, they also had the ability to assemble an army without immediate detection by the Umayyad state.
The Abbasids and the Khurasanis were joined by one other conspiratorial region: Kufa, and Iraq in general. Iraqis generally believed that the Prophet’s family should be returned to power. They had in mind a descendant of Ali, just as they had recently begun to back Zayd’s rebellion. But the Abbasids were close enough to the Prophet’s family that they could keep options open. The conspirators all agreed that if they could overthrow the Umayyads, the next Caliph would be someone chosen from the Prophet’s family, with the exact choice of an individual held in abeyance until the revolt was successful.
Criticism of the Umayyads had begun much earlier, during the reigns of the short-lived weaker Umayyads. The Abbasids criticized the luxury of the Umayyads to anyone who asked. They chose black as their standard; wearing black was a signal of support for the Abbasids. They promised to return the Umma to pure desert morals and simplicity. When today’s Islamic extremists choose black as their color, they are evoking the Abbasids’ cause, comparing current rulers to the Umayyads.
- Caliphate: The History of an Idea, by Hugh Kennedy