Book excerpt: A study of the longue durée of a marginalized part of northern Kenya, examining the process of territorialization and the role of Islam in politicizing ethnicity. The recent ethnic violence in Kenya has been preceded by a process of territorialization and politicization of ethnicity. This study examines a marginalized part of Kenya, the semi-arid north inhabited by pastoralists of three language groups - speakers of Oromo, Somali, and Rendille. It spans different periods of time, from early processes of ethnic differentiation between groups, through the colonial period when differences were reflected in administrative policies, to recent times, when global minority discourses, particularly those related to Islam, are tapped by local political agents and ethnic entrepreneurs. A companion volume to Pastoralism and Politics in Northern Kenya and Southern Ethiopia, this book is based on over thirty-four years of field research and synthesizes findings from history and political anthropology. Günther Schlee is director of the Department of 'Integration and Conflict', Max Planck Institute for Social Anthropology, Halle, Germany; Abdullahi Shongolo is an independent scholar based in Kenya.