The Kharijites were a group of ultra-pious secessionists, the most extremists of whom were given to excessive use of arms against those who disagreed with their doctrine. They emerged during the First Fitna from the Kufan pietists in the army of Caliph Ali (). They waged war against the governments of Ali and later the Umayyads and Zubayrids, all of whom they viewed as illegitimate rulers. By the time of the Second Fitna, the Iraqi garrison town of Basra had become an epicenter of the Kharijite faction of the Azariqa. Expelled by Zubayrid armies, they fled to the eastern provinces of Fars and Kirman, both dependencies of Basra, frequently raiding the city and its suburbs. Mus'ab sent his most experienced commander, Muhallab ibn Abi Sufra, against them to recover the provinces. Although Muhallab was able to prevent Azariqa raids against Basra, his war lasted years, draining Zubayrid resources. Mus'ab also sent armies against the Najdat Kharijites, who controlled Bahrayn, but the campaigns ended in failure.