The Abbasid caliphs were Arabs descended from Abbas ibn Abd al-Muttalib, one of the youngest uncles of Muhammad and of the same Banu Hashim clan.
The Abbasids claimed to be the true successors of Prophet Muhammad in replacing the Umayyad descendants of Banu Umayya by virtue of their closer bloodline to Muhammad.

The Abbasids also distinguished themselves from the Umayyads by attacking their moral character and administration in general.
According to Ira Lapidus, "The Abbasid revolt was supported largely by Arabs, mainly the aggrieved settlers of Merv with the addition of the Yemeni faction and their Mawali".
The Abbasids also appealed to non-Arab Muslims, known as mawali, who remained outside the kinship-based society of the Arabs and were perceived as a lower class within the Umayyad empire.
Muhammad ibn 'Ali, a great-grandson of Abbas, began to campaign in Persia for the return of power to the family of Prophet Muhammad, the Hashimites, during the reign of Umar II.

During the reign of Marwan II, this opposition culminated in the rebellion of Ibrahim al-Imam, the fourth in descent from Abbas.
Supported by the province of Khorasan (Eastern Persia), even though the governor opposed them, and the Shia Arabs, he achieved considerable success, but was captured in the year 747 and died, possibly assassinated, in prison.

On 9 June 747 (15 Ramadan AH 129), Abu Muslim, rising from Khorasan, successfully initiated an open revolt against Umayyad rule, which was carried out under the sign of the Black Standard.
Close to 10,000 soldiers were under Abu Muslim's command when the hostilities officially began in Merv.
General Qahtaba followed the fleeing governor Nasr ibn Sayyar west defeating the Umayyads at the Battle of Gorgan, the Battle of Nahāvand and finally in the Battle of Karbala, all in the year 748.

The quarrel was taken up by Ibrahim's brother Abdallah, known by the name of Abu al-'Abbas as-Saffah, who defeated the Umayyads in 750 in the battle near the Great Zab and was subsequently proclaimed caliph.
After this loss, Marwan fled to Egypt, where he was subsequently assassinated.
The remainder of his family, barring one male, were also eliminated.

Immediately after their victory, As-Saffah sent his forces to Central Asia, where his forces fought against Tang expansion during the Battle of Talas.
The noble Iranian family Barmakids, who were instrumental in building Baghdad, introduced the world's first recorded paper mill in the city, thus beginning a new era of intellectual rebirth in the Abbasid domain.
As-Saffah focused on putting down numerous rebellions in Syria and Mesopotamia.
The Byzantines conducted raids during these early distractions.
The Abbasid caliphs were Arabs descended from Abbas ibn Abd al-Muttalib, one of the youngest uncles of Muhammad and of the same Banu Hashim clan. The Abbasids claimed to be the true successors of Prophet Muhammad in replacing the Umayyad descendants of Banu Umayya by virtue of their closer bloodline to Muhammad.
The Abbasids also distinguished themselves from the Umayyads by attacking their moral character and administration in general. According to Ira Lapidus, "The Abbasid revolt was supported largely by Arabs, mainly the aggrieved settlers of Merv with the addition of the Yemeni faction and their Mawali". The Abbasids also appealed to non-Arab Muslims, known as mawali, who remained outside the kinship-based society of the Arabs and were perceived as a lower class within the Umayyad empire. Muhammad ibn 'Ali, a great-grandson of Abbas, began to campaign in Persia for the return of power to the family of Prophet Muhammad, the Hashimites, during the reign of Umar II.
During the reign of Marwan II, this opposition culminated in the rebellion of Ibrahim al-Imam, the fourth in descent from Abbas. Supported by the province of Khorasan (Eastern Persia), even though the governor opposed them, and the Shia Arabs, he achieved considerable success, but was captured in the year 747 and died, possibly assassinated, in prison.
On 9 June 747 (15 Ramadan AH 129), Abu Muslim, rising from Khorasan, successfully initiated an open revolt against Umayyad rule, which was carried out under the sign of the Black Standard. Close to 10,000 soldiers were under Abu Muslim's command when the hostilities officially began in Merv. General Qahtaba followed the fleeing governor Nasr ibn Sayyar west defeating the Umayyads at the Battle of Gorgan, the Battle of Nahāvand and finally in the Battle of Karbala, all in the year 748.
The quarrel was taken up by Ibrahim's brother Abdallah, known by the name of Abu al-'Abbas as-Saffah, who defeated the Umayyads in 750 in the battle near the Great Zab and was subsequently proclaimed caliph. After this loss, Marwan fled to Egypt, where he was subsequently assassinated. The remainder of his family, barring one male, were also eliminated.
Immediately after their victory, As-Saffah sent his forces to Central Asia, where his forces fought against Tang expansion during the Battle of Talas. The noble Iranian family Barmakids, who were instrumental in building Baghdad, introduced the world's first recorded paper mill in the city, thus beginning a new era of intellectual rebirth in the Abbasid domain. As-Saffah focused on putting down numerous rebellions in Syria and Mesopotamia. The Byzantines conducted raids during these early distractions.
Abbasid Caliphate