The archaeological record of southeastern Mauritania has considerable potential to contribute to longstanding anthropological debates in world prehistory, such as early cereal domestication or the emergence and organization of complex societies, although research remains limited. The archaeological study of funerary rites offers invaluable insights into cultural attitudes towards the dead and the socio-economic dynamics of the living. The materiality of remembrance is a political statement, rooted on the ability of different social agents to mobilize labor pools and networks of obligations within a given cultural framework. As such, understanding the spatial distribution and size variability in burial monuments within funerary landscapes provides insights into the social energetics of ancestor memorialization. To that end, this paper first presents a size-based classification system for pre-Islamic conical tumulus cairns in the highlands of southeastern Mauritania, West Africa, that has much wider applicability within prehistoric Saharan archaeology. Through the first application of Gini coefficients to the study of funerary landscapes, the paper then analyses the spatial distribution and degree of monument size variability within large, spatially bounded clusters (“tumulus fields”) in Dhar Tichitt in order to contextualize the socio-economic dynamics of labor mobilization at three previously undocumented tumulus fields in the western Tagant Plateau.