Mukhtar al-Thaqafi
The death of Husayn produced widespread outcry and helped crystallize opposition to Yazid into an anti-Umayyad movement based on Alid aspirations. The Battle of Karbala contributed to the definitive break between what later became the Shi'a and Sunni denominations of Islam. This event catalyzed the transformation of Shi'ism, which hitherto had been a political stance, into a religious phenomenon. To this day it is commemorated each year by Shi'a Muslims on the Day of Ashura. This period also saw the end of purely Arab Shi'ism in the revolt of Mukhtar al-Thaqafi, who mobilized the marginalized and socioeconomically exploited "mawali" by redressing their grievances. Before then, non-Arab Muslims had not played any significant political role. Despite its immediate political failure, Mukhtar's movement was survived by the Kaysanites, a radical Shi'a sect, who introduced novel theological and eschatological concepts that influenced the later development of Shi'ism. The Abbasids exploited the underground network of Kaysanite propagandists during their revolution and the most numerous among their supporters were Shi'a and non-Arabs.