The article discusses methods to approach events and processes in indigenous irrigation prior to recorded history or from sparsely documented history. Kilimanjaro in Tanzania remains the largest centre of traditional hill furrows in eastern Africa. A considerable infrastructure was developed before the 20th century, supporting relatively dense population concentrations. It is argued that the establishment and management of the canal infrastructure depended on institutions which could contribute to knowledge of the development of irrigated agriculture. The method uses oral history to study two patrilineages and their relationship to the canals in their neighbourhood on Mt. Kilimanjaro. The development of the local irrigation traditions is central to the history of settlement and livelihoods the region, and of relevance to the history of intensive agriculture.