They were decisively defeated by 'Ali, who was in turn assassinated by a Kharijite. Kharijites engaged in guerilla warfare against the Umayyads, but only became a movement to be reckoned with during the second civil war when they at one point controlled more territory than any of their rivals. Kharijites were, in fact, one of the major threats to Ibn al-Zubayr's bid for the caliphate; during this time they controlled Yamama and most of southern Arabia and captured the oasis town of al-Ta'if.[1]