Mu'awiya in the context of Diyar Rabi'a

The Battle of Nahrawan (Arabic: مَعْرَكَة النَّهْرَوَان, romanized: Ma'rakat an-Nahrawān) was fought between the army of the fourth Rashidun caliph Ali and the rebel group Kharijites in July 658 CE (Safar 38 AH). The latter were a group of erstwhile allies of Ali during the First Fitna. They separated from him following the Battle of Siffin when Ali agreed to settle the dispute with Mu'awiya, governor of Syria, through negotiations, a move labeled by the group as against the Qur'an. After failed attempts to regain their loyalty and because of their rebellious and violent activities, Ali confronted the Kharijites near their headquarters by the Nahrawan Canal, near modern-day Baghdad. Of the 4,000 rebels, some 1,200 were won over with the promise of amnesty while the majority of the remaining 2,800 rebels were killed in the ensuing battle. Other sources put the casualties at 1500–1800.

The battle resulted in a permanent split between the group and the rest of the Muslims, whom the Kharijites branded as apostates. Although defeated, they continued to threaten and harass cities and towns for several years. Ali was assassinated by a Kharijite in January 661.

Abū Muḥammad Maʿdīkarib ibn Qays ibn Maʿdīkarib (599–661), better known as al-Ashʿath (Arabic: الأشعث), was a chief of the Kinda tribe of Hadhramawt and founder of a leading noble Arab household in Kufa, one of the two main garrison towns and administrative centers of Iraq under the Rashidun (632–661) and Umayyad (661–750) caliphs.

Al-Ash'ath embraced Islam in the presence of the Islamic prophet Muhammad only to leave the faith following the latter's death in 632. He led his tribesmen against the Muslims during the Ridda wars but surrendered during a siege of his fortress, after which many Kindites were executed. He was imprisoned, but pardoned by Caliph Abu Bakr (r. 632–634) upon his repentance. Al-Ash'ath joined the Muslim conquests of Mesopotamia and Persia, fighting in several battles between 636 and 642. He settled in the newly-founded garrison city of Kufa and became the leader of his tribesmen there. Under Caliph Uthman (r. 644–656), al-Ash'ath governed Adharbayjan. In 657, he fought as a commander in the Battle of Siffin for Caliph Ali (r. 656–661) against Mu'awiya, but supported an end to the battle by arbitration, for which generally pro-Alid sources consider him a traitor. When Mu'awiya became caliph after Ali was assassinated in 661, the position of al-Ash'ath and his family was strengthened in Kufa, where he soon after died.