Ahmet T. Karamustafa bases this study on a fresh reading of the primary sources and, by integrating the findings of recent scholarship on the subject, presents a unified narrative of Sufism's historical development. His innovative analytical framework reveals the emergence of mystical currents in Islam during the ninth century and traces the rapid spread of Iraq-based Sufism to other regions of the Islamic world, providing an integrated, comprehensive understanding of one of the most compelling aspects of late antique, early medieval Islamic religious history. Edinburgh University Press