Abbasid revolution
The Abbasid revolution, was the overthrow of the Umayyad Caliphate, the second of the four major caliphates in Islamic history, by the third, the Abbasid Caliphate.
The Abbasid revolt originated in the eastern province of Khorasan in the mid-8th century, fueled by widespread discontent with Umayyad rule. The Abbasids, claiming descent from Muhammad's uncle Abbas, capitalized on various grievances, including discrimination against non-Arabs, heavy taxation, and perceived impiety of Umayyad rulers. Led by a Persian revolutionary using the nom-de-guerre Abu Muslim, Abu Muslim's strategy lay in unifying the grievances of the native Iranian landowning class with the heavily Persianized Arab settler minority in Khorasan, both heavily disillusioned with Umayyad rule. Marching under black banners, they formed a powerful force that swept westward in open revolt, defeating Umayyad forces. The decisive Battle of the Zab in 750 saw the Abbasid army triumph over the last Umayyad caliph, Marwan II. This victory led to the fall of the Umayyad dynasty and the establishment of Abbasid rule, marking a significant shift in the caliphate's power base from Syria to Iraq and ushering in a new era of Islamic governance.
Background
By the 740s, the Umayyad Empire found itself in critical condition. A succession crisis in 744 led to the Third Fitna, which raged across the Middle East for three years. The very next year, al-Dahhak ibn Qays al-Shaybani initiated a Kharijite rebellion that would continue until 746. Concurrent with this, a rebellion broke out in reaction to Marwan II's decision to move the capital from Damascus to Harran, resulting in the destruction of Homs – also in 746. It was not until 747 that Marwan II was able to pacify the provinces; the Abbasid revolution began within months.Nasr ibn Sayyar was appointed governor of Khorasan by Hisham ibn Abd al-Malik in 738. He held on to his post throughout the war of succession, being confirmed as governor by Marwan II in the aftermath.
Khorasan's expansive size and low population density meant that the Arab denizens – both military and civilian – lived largely outside of the garrisons built during the spread of Islam into Persia. This was in contrast to the rest of the Umayyad provinces, where Arabs tended to seclude themselves in fortresses to avoid interacting with the locals. Arab settlers in Khorasan left their traditional lifestyle and settled among the native Iranian peoples. While intermarriage with non-Arabs elsewhere in the Empire was discouraged or even banned, it slowly became a habit within eastern Khorasan; and the Arabs began adopting Persian dress and as the two languages influenced one another, the ethnic barriers gradually eroded.
Causes
Support for the Abbasid revolution came from people of diverse backgrounds, with almost all levels of society supporting armed opposition to Umayyad rule. This was especially pronounced among Muslims of non-Arab descent, though even Arab Muslims resented Umayyad rule and centralized authority over their nomadic lifestyles. Both Sunnis and Shias supported efforts to overthrow the Umayyads, as did non-Muslim subjects of the empire who resented religious discrimination.Discontent among Shia Muslims
Following the Battle of Karbala, which led to the massacre of Husayn ibn Ali, the grandson of the prophet Muhammad, alongside his kin and companions by the Umayyad army in 680 CE, the event became a rallying cry of opposition against the Umayyads. The Abbasids also used the memory of Karbala extensively to gain popular support against the Umayyads, which further rallied Shi'ite support. In the decades preceding the Abbasid revolution, several Shi'ite and Alid uprisings had taken place against the Umayyads. To an extent, rebellion against the Umayyads bore an early association with Shi'ite ideas. This included the Tawwabin uprising led by Sulayman ibn Surad in 684–685 and Mukhtar al-Thaqafi's uprising in 685–687, following the murder of Husayn ibn Ali in 680. Later on, the Revolts of Zayd ibn Ali in 740 and the uprising of Abd Allah ibn Mu'awiya in 747–748, who even established temporary rule over Iran, paved way for the Abbasid revolution.The Hashimiyya movement was largely responsible for starting the final efforts against the Umayyad dynasty, initially with the goal of replacing the Umayyads with an Alid ruling family. Initially, the Abbasid family kept quiet about their identity, simply stating that they wanted a ruler from the descendant of Muhammad upon whose choice as caliph the Muslim community would agree to. Many Shi'ites naturally assumed that this meant an Alid ruler, a belief which the Abbasids tacitly encouraged to gain Shi'ite support. The Abbasids claimed that Abu Hashim, the grandson of Ali through his son Muhammad ibn al-Hanafiyyah, had formally transferred the Imamate to Muhammad ibn Ali ibn Abdallah in 717, and thus Imamah was transferred to the house of al-Abbas.
Although the anecdote is considered a fabrication, at the time it allowed the Abbasids to rally the supporters of the failed revolt of Mukhtar al-Thaqafi, who had represented themselves as the supporters of Muhammad ibn al-Hanafiyya. By the time the revolution was in full swing, most Kaysanite Shia had either transferred their allegiance to the Abbasid dynasty, or differed to other branches of Shi'ism, and so the Kaysanites ceased to exist.
Discontent among non-Arab Sunni Muslims
The Umayyad state is remembered as an Arab-centric state, being run by and for the benefit of those who were ethnically Arab though Muslim in creed. The non-Arab Muslims resented their marginal social position and were easily drawn into Abbasid opposition to Umayyad rule. Arabs dominated the bureaucracy and military, and were housed in fortresses separate from the local population outside of Arabia. Even after converting to Islam, non-Arabs or Mawali could not live in these garrison cities. The non-Arabs were not allowed to work for the government nor could they hold officer positions in the Umayyad military and they still had to pay the jizya tax for non-Muslims. Non-Muslims under Umayyad rule were subject to these same injunctions. Racial intermarriage between Arabs and non-Arabs was rare. When it did occur, it was only allowed between an Arab man and a non-Arab woman while non-Arab men were generally not free to marry Arab women.Conversion to Islam occurred gradually. If a non-Arab wished to convert to Islam, they not only had to give up their own names but also had to remain a second-class citizen. The non-Arab would be "adopted" by an Arab tribe, though they would not actually adopt the tribe's name as that would risk pollution of perceived Arab racial purity. Rather, the non-Arab would take the last name of "freedman of al-", even if they were not a slave prior to conversion. This essentially meant they were subservient to the tribe who sponsored their conversion.
Although converts to Islam made up roughly 10% of the native population – most of the people living under Umayyad rule were not Muslim – this percent was significant due to the very small number of Arabs. Gradually, the non-Arab Muslims outnumbered the Arab Muslims, causing alarm among the Arab nobility. Socially, this posed a problem as the Umayyads viewed Islam as the property of the aristocratic Arab families. There was a rather large financial problem posed to the Umayyad system as well. If the new converts to Islam from non-Arab peoples stopped paying the jizya tax stipulated by the Qur'an for non-Muslims, the empire would go bankrupt. This lack of civil and political rights eventually led the non-Arab Muslims to support the Abbasids, despite the latter also being Arab.
Even as the Arab governors adopted the more sophisticated Iranian methods of governmental administration, non-Arabs were still prevented from holding such positions. Non-Arabs were not even allowed to wear Arabian style clothing, so strong were the feelings of Arab racial superiority cultivated by the Umayyads. Much of the discontent this caused led to the Shu'ubiyya movement, an assertion of non-Arab racial and cultural equality with Arabs. The movement gained support among Egyptians, Arameans and Berber people, though this movement was most pronounced among Iranian people.
Repression of Iranian culture
The early Muslim conquest of Persia was coupled with an anti-Iranian Arabization policy which led to much discontent. Up until the time of Abd al-Malik ibn Marwan, the divan was dominated by the mawali and accounts were written using the Pahlavi script. The controversial Umayyad governor Al-Hajjaj ibn Yusuf forced all the mawali who had left for cities, in order to avoid paying the kharaj tax, to return to their lands. He was upset at the usage of Persian as the court language in the eastern Islamic empire, and ordered it to be changed to Arabic.Discontent among non-Muslims
Support for the Abbasid revolution was an early example of people of different faiths aligning with a common cause. This was due in large part to policies of the Umayyads which were regarded as particularly oppressive to anyone following a faith other than Islam. In 741, the Umayyads decreed that non-Muslims could not serve in government posts. The Abbasids were aware of this discontent, and made efforts to balance both its Muslim character as well as its partially non-Muslim constituency.The non-Muslim aristocracy around Merv supported the Abbasids, and thus retained their status as a privileged governing class regardless of religious belief.
Historical events
Buildup
Beginning around 719, Hashimiyya missions began to seek adherents in Khurasan. Their campaign was framed as one of proselytism. They sought support for "a member of the House of the Prophet who shall be pleasing to everyone", without making explicit mention of the Abbasids. These missions met with success both among Arabs and non-Arabs, although the latter may have played a particularly important role in the growth of the movement. A number of Shi'ite rebellions – by Kaysanites, Hashimiyya and mainstream Shi'ites – took place in the final years of Umayyad rule, just around the same time that tempers were flaring among the Syrian contingents of the Umayyad army regarding alliances and wrongdoings during the Second and Third Fitna.At this time Kufa was the center for the opposition to Umayyad rule, particularly Ali's supporters and Shias. In 741–42 Abu Muslim made his first contact with Abbasid agents there, and eventually he was introduced to the head of Abbasids, Imam Ibrahim, in Mecca. Around 746, Abu Muslim assumed leadership of the Hashimiyya in Khurasan. Unlike the Alid revolts which were open and straightforward about their demands, the Abbasids along with the Hashimite allies slowly built up an underground resistance movement to Umayyad rule. Secret networks were used to build a power base of support in the eastern Muslim lands to ensure the revolution's success. This buildup not only took place right on the heels of the Zaydi Revolt in Iraq, but also concurrently with the Berber Revolt in Iberia and Maghreb, the Ibadi rebellion in Yemen and Hijaz, and the Third Fitna in the Levant, with the revolt of al-Harith ibn Surayj in Khurasan and Central Asia occurring concurrently with the revolution itself. The Abbasids spent their preparation time watching as the Umayyad Empire was besieged from within itself in all four cardinal directions, and School of Oriental and African Studies Professor Emeritus G. R. Hawting has asserted that even if the Umayyad rulers had been aware of the Abbasids' preparations, it would not have been possible to mobilize against them.