Book excerpt: A fascinating, in-depth exploration of the messianic idea in Sunni Islam through four significant movements from different times and places Expectation of a redeemer is a widespread phenomenon across many civilisations. Classical Islamic traditions maintain that this redeemer will transform our world for the better in collaboration with Jesus, who will return as a Muslim and play a central role in this apocalyptic endeavour. While the messianic idea occupies a central place in Shi‘i thought, there have also been numerous Sunni claimants throughout history – though they have received less scholarly attention. In this groundbreaking work, Yohanan Friedmann explores the roots of the messianic idea in Sunni Islam, and studies four major mahdi claimants – Ibn Tumart, Sayyid Muhammad Jawnpuri, Muhammad Ahmad and Mirza Ghulam Ahmad – who made a considerable impact in the region where they emerged. Focusing on their religious thought, and relating it to classical Muslim ideas on the apocalypse, he examines their movements and considers their achievements, failures and legacies.