The Abbasid Revolution in 750 CE,^[34] led by the Iranian general Abu Muslim Khorasani, marked a significant shift in the Islamic empire. The Abbasid army, comprising both Iranians and Arabs, overthrew the Umayyad Caliphate, signaling the end of Arab dominance and the beginning of a more inclusive, multi-ethnic state in the Middle East.^[35]

One of the Abbasids' first actions was to move the capital from Damascus to Baghdad,^[36] founded in 762 on the Tigris River in a region influenced by Persian culture. This move was partly in response to demands from Persian mawali, who sought reduced Arab influence. The Abbasids introduced the role of vizier in their administration, a position similar to a vice-caliph, which led to many caliphs adopting more ceremonial roles. This change, along with the rise of a new Persian bureaucracy, marked a clear departure from the Umayyad era.

By the 9th century, the Abbasid Caliphate's control weakened as regional leaders emerged, challenging its authority.^[36] The caliphs began employing Mamluks, Turkic-speaking warriors, as slave soldiers. Over time, these mamluks gained significant power, eventually overshadowing the caliphs.^[34]

This period also saw uprisings like the Khurramite movement, led by Babak Khorramdin in Azerbaijan, advocating for Persian independence and a return to the pre-Islamic Iranian glory. This movement lasted over twenty years before its suppression.^[37]

Various dynasties rose in Iran during the Abbasid period, including the Tahirids in Khorasan, the Saffarids in Sistan, and the Samanids, who extended their rule from central Iran to Pakistan.^[34]

In the early 10th century, the Buyid dynasty, a Persian faction, gained substantial power in Baghdad, effectively controlling the Abbasid administration. The Buyids were later defeated by the Seljuq Turks, who maintained nominal allegiance to the Abbasids until the Mongol invasion in 1258, which ended the Abbasid dynasty.^[36]

The Abbasid era also saw the empowerment of non-Arab Muslims (mawali) and a shift from an Arab-centric empire to a Muslim empire. Around 930 CE, a policy was introduced requiring all empire bureaucrats to be Muslim.