What is a caliphate? Who can be caliph? And how are contemporary ideologues such as ISIS reviving – and abusing – the term today? In the first modern account of a subject of critical importance today, acclaimed historian Hugh Kennedy answers these questions by chronicling the rich history of the caliphate, from the death of Muhammad to the present. At its height, the caliphate stretched from Spain to China and was the most powerful political entity in western Eurasia. In an era when Paris and London boasted a few thousand inhabitants, Baghdad and Cairo were sophisticated centres of trade and culture, and the Ummayad and Abbasid caliphates were distinguished by extraordinary advances in science, medicine and architecture. By ending with the recent re-emergence of caliphal ideology within fundamentalist Islam, The Caliphate underscores why it is crucial that we understand this form of Islamic government before groups such as ISIS distort its practice completely.