Wahhabism is a conservative branch of Islam originating in the eighteenth century. This collection of British government documents details the importance of the Wahhabi tradition in the power politics of Saudi Arabia, where it has become the dominant form of Islam. Perhaps the most important primary source for the history of Arabia, these British archives describe vividly the complicated ways in which three incarnations of the Sa'udi state used religion for political ends. The end result was the unification of much of the peninsula into the Kingdom of Saudi Arabia. Against this background, the Sa'udis' relationship with the British presented them with a challenge because they could not reconcile it within their established paradigms of religious thought. They had to handle the British pragmatically and, ultimately, had to accept the transformation of their Islamic polity into a territorially delineated state. In this sense, the encounter with the British became the defining one for the Sa'udis in terms of their external relations and place within the international system.