The rapid expansion of the early Islamic world is conventionally ascribed to a combination of brilliant military leadership and religious fervour. In this book, Abd al-Aziz Duri demonstrates how the growth, development and durability of early Islamic governance derived from highly sophisticated systems of administration (in which the idea of a Muslim ummah was the central feature) as well as efficient mechanisms for taxation and tax collection. The fact that in a highly dynamic period of Islamic history a seamless system of administration could endure for several centuries, from the early Muslim conquests and the later Umayyad era to the end of Abbasid rule, is testimony to the political and organisational skills of these early Muslim leaders. Duri's work makes a major contribution to our understanding of how Islam established itself and flourished as a lasting major force in the development of world history.