In August 1927, British colonial authorities arrested Hamman Yaji, Emir of Madagali, an infamous slave trader who had terrorized the neighboring montagnard populations of the Northern Cameroons and bedeviled the colonial administrations of three nations. His diary was seized and soon became a fabled document in northern Nigerian history. Written in Arabic and translated into English by a British colonial official, the diary chronicles Hamman Yaji's daily activities between 1912 and 1927.

He recorded his daily routine - where he traveled, his slaving raids and slave-trading activities, visitors and gifts received, his relations with friends and family and with the British administration, and his practice of Islam.

This rare and remarkable document, made accessible to scholars for the first time since its composition more than seventy-five years ago, is enhanced by a substantial introduction that places Hamman Yaji in historical and cultural perspective and describes the diary's discovery and translation, and its significance for British colonial and West African history.