Definitive and insightful, in this richly layered and engrossing account, John McHugo reveals how the great divide in Islam occurred. Charting the story of Islam from the death of the Prophet Muhammad to the present day, he describes the conflicts that raged over the succession to the Prophet, how Sunnism and Shi`ism evolved as different sects during the Abbasid caliphate, and how the rivalry between the empires of the Sunni Ottomans and Shi`i Safavids contrived to ensure that the split would continue into modern times. Now its full, destructive force has been brought out by the struggle between Saudi Arabia and Iran for the soul of the Muslim world.