Cattle were independently domesticated from the aurochs, a wild bovine species, in the vicinity of the current countries of Turkey and Pakistan ∼10,000 y ago. Cattle have since spread with humans across the world, including to regions where these two distinct lineages have hybridized. Using genomic tools, we investigated the ancestry of cattle from across the world. We determined that the descendants of the cattle brought to the New World by the Spanish in the late 1400s show ancestry from multiple domesticated lineages. This pattern resulted from pre-Columbian introgression of genes from African cattle into southern Europe.