The authoritative account of the sectarian division that for centuries has shaped events in the Middle East and the Islamic world. In 632, soon after the prophet Muhammad died, a struggle broke out among his followers as to who would succeed him. The majority argued that the new leader of Islam should be elected by the community''s elite. Others believed only members of Muhammad''s family could lead. This dispute over who should guide Muslims, the appointed Caliph or the bloodline Imam, marks the origin of the Sunni-Shii split in Islam. Toby Matthiesen explores this hugely significant division from its origins to the present day. Moving chronologically, his book sheds light on the many ways that it has shaped the Islamic world, outlining how over the centuries Sunnism and Shiism became Islams two main branches, particularly after the Muslim Empires embraced sectarian identity. It reveals how colonial rule institutionalised divisions between Sunnism and Shiism both on the Indian subcontinent and in the greater Middle East, giving rise to pan-Islamic resistance and Sunni and Shii revivalism. It then focuses on the fall-out from the 1979 revolution in Iran and the US-led military intervention in Iraq. As Matthiesen shows, however, though Sunnism and Shiism have had a long and antagonistic history, most Muslims have led lives characterised by confessional ambiguity and peaceful co-existence. Tensions arise when sectarian identity becomes linked to politics. Based on a synthesis of decades of scholarship in numerous languages, The Caliph and the Imam will become the standard text for readers looking for a deeper understanding of contemporary sectarian conflict and its historical roots.