Of the numerous movements and theological schools in medieval Islam, only Shi‘ism (the “party of ‘Ali”; Arab. shi‘at ‘Ali ) was able to create a viable and lasting alternative to Sunnism. The success of the Shi‘ites came at a cost: as the Shi‘ite doctrine grew more sophisticated and its adherents more numerous, politically active, and organized, both the caliphs and the leaders of the Sunni community came to view the Shi‘ites as their principal political and religious rivals. As a result, the Sunni ruling elite did their utmost to prevent Shi‘ite candidates from gaining political power, whereas Sunni theologians spared no effort to discredit Shi‘ism on doctrinal grounds. In sum, throughout the Middle Ages and into the modern period, the Shi‘ites have had to defend themselves both politically and ideologically, often against great odds.