A new genomic study reveals that the oldest known domesticated horse population, which lived on the Central Asian steppes roughly 5,500 years ago, did not sire the domesticated horses of today. Their lineage does persist, however, in the form of feral horses. The oldest culture known to domesticate horses is the Botai, a group who once lived in modern day Kazakhstan. At ancient Botai sites, there are clear signs of horse domestication, such as equestrian-related tools and milk residues on ceramics. Yet whether these steeds were the founding ancestors of modern domesticated horses remains unknown. Here, Charleen Gaunitz and colleagues analyzed the genomes of 88 ancient and modern horses, including 20 Botai horses, from a range of eras and locations across Eurasia. The data reveal that none of the domesticated horses in the sample are descendent from the original Botai group, yet seven Przewalski's horses, an endangered group of feral horses that roam Central Asian, are, the authors report. Thus, they propose that, by 3,000 BCE at the latest, a different group of horses became the source of all domestic populations that expanded thereafter. Unfortunately, few horse genomes have been recovered from this era, meaning that the population of horses that founded domesticated horses as we know them today will remain a mystery, for now.