Rogerson’s timely book begins with the contemporary Middle East and the proxy wars between Saudi Arabia and its Sunni allies and Shiite Iran. To understand these, he suggests, we must understand the origins of the Sunni-Shia divide, which go back to the death of the Prophet Muhammad in 632, the accidental coup that set aside the claims of his son Ali, and the slaughter of Ali’s own son Husayn at Kerbala. These events, known to every Muslim, have created a slender fault line in the Middle East.