Scholar, mystic and visionary, Ibn 'Alwan lived through the transition from Ayyubid to Rasulid rule in thirteenth-century Yemen. He was well known in his time for his critique of the ruling elites and their governance, and left behind a substantial body of writings on Islamic mysticism, theology, law and exegesis of the Qur'an. Here Muhammad Aziz presents a comprehensive portrait of Ibn 'Alwan, delineating the religious and political background in Yemen, the development of Sufi orders, the interplay between Sufi, Shi'i and Sunni traditions, and the impact of Ibn 'Alwan on the history of Sufism and Islam. The first study of Ibn 'Alwan in English, "Religion and Mysticism in Early Islam" is essential reading for all those interested in mysticism, early Islam, Sufism, and religion and history more generally.