Cemeteries on a moving frontier: Mortuary practices and the spread of pastoralism from the Sahara into eastern Africa

Today, pastoral systems in eastern Africa are supported by elaborate social networks that minimize risk and facilitate the movement of people, animals, and resources across unpredictable, semi-arid landscapes. Although similar structures must have existed in the past, investigations into early herders' social lives remain underdeveloped. The African archaeological record is exceptional in that monumental burial grounds are a hallmark of early pastoral lifeways as they spread from the Sahara through eastern Africa ∼8000-2000 BP. We review archaeological evidence for pastoralist cemeteries in these regions to ask what role(s) burial grounds played in the transmission of mobile food production. To do so, we invoke a 'moving frontier' framework in which social and economic strategies fluctuate during the initial spread of food production, then become more rigid after land use and relationships stabilize on a 'static frontier.' Ethnographically-documented mortuary practices among recent eastern African pastoralists provide a model for a static frontier, and reveal emic motivations that could not be drawn from archaeological data alone. Although cemeteries are rare in the ethnographic record, archaeological and ethnohistoric practices form a long gradient of mortuary behaviours that fluctuate in response to changing conditions, and help establish and reify social networks among herders facing instability.