The megalithic pillar sites found around Lake Turkana, Kenya, are monumental cemeteries built approximately 5000 years ago. Their construction coincides with the spread of pastoralism into the region during a period of profound climate change. Early work at the Jarigole pillar site suggested that these places were secondary burial grounds. Subsequent excavations at other pillar sites, however, have revealed planned mortuary cavities for predominantly primary burials, challenging the idea that all pillar sites belonged to a single ‘Jarigole mortuary tradition’. Here, the authors report new findings from the Jarigole site that resolve long-standing questions about eastern Africa's earliest monuments and provide insight into the social lives, and deaths, of the region's first pastoralists.