At some point during the Muslim conquests, the Taghlib switched allegiance to the Muslims whilst retaining their Christian faith. Among the most prominent defectors was Utba ibn al-Waghl, a Kufa-based activist from the Sa'd line of the Jusham division. Much of the Taghlibi troops of the Muslim army settled in Kufa. Their eventual defection to the Muslims and Caliph Umar ibn al-Khattab's embrace of their support gained the Taghlib a special exemption from the poll tax collected from the Caliphate's Christian subjects. During the First Muslim Civil War (656–661), members of the Taghlib fought on the side of Ali ibn Abi Talib at the Battle of the Camel (656) and the Battle of Siffin (657). However, at Siffin, a significant Taghlibi force also fought alongside Mu'awiya .