Using excavation and radiocarbon dating, the authors show that construction of megalithic pillar sites begins in eastern Africa by the fifth millennium BP, and is contemporary with the earliest herding in the region. Mobile herders and/or hunter-gatherers built and used these sites in a dynamic context of economic and social change. We are more familiar with monumentality as an adjunct of cereal cultivators—but this study demonstrates a relationship between early herding and monuments, with clear relevance to pre-cultivation monumentality of very much earlier periods elsewhere.