show Abstracthide AbstractNow extinct, the aurochs (Bos primigenius) was a keystone species in prehistoric Eurasian and North African ecosystems, and the progenitor of cattle (Bos taurus), a domesticate that has provided people with food and labour for millennia. Here we analysed 38 ancient genomes that revealed four distinct ancestries of aurochs: European, Near Eastern, North Asian and South Asian, each of which has dynamic trajectories that have responded to changes in climate and culture. Like Homo heidelbergensis, aurochsen first entered Europe ~650 kya, but these early populations leave only trace ancestry after population replacement from the east ~90 kya during an MIS5 warm period before the onset of the most recent glaciation. Asian and European populations then remained separated by habitat fragmentation until mixing following the climate amelioration of the early Holocene. European aurochsen endured the more severe bottleneck during the Last Glacial Maximum, retreating to southern refugia before recolonising from Iberia. Domestication involved limited capture of a southwest Asian aurochs population, followed by early and pervasive male-mediated admixture with each ancestral strain of aurochs after domestic stocks dispersed beyond their Near Eastern region of origin.