The study investigates the timeline and context of horse domestication and the rise of widespread horse-based mobility in Eurasia. By analyzing 475 ancient horse genomes, the researchers found that reproductive control of modern domestic horses (DOM2) emerged around 2200 BCE through close-kin mating and shortened generation times. This marked the beginning of significant horse-based mobility, which coincided with a severe domestication bottleneck starting around 2700 BCE. The expansion of DOM2 horses across Eurasia ultimately replaced nearly every local horse lineage. The study also detected shortened generation times at the Botai settlement around 3500 BCE, suggesting local horse husbandry before the rise of modern domestic bloodlines. The findings challenge the common narrative of large horse herds accompanying steppe migrations around 3000 BCE and earlier, indicating that horse-based mobility developed much later. The research provides new insights into the genetic and demographic changes in horses during this period, supporting the idea that horse domestication was a multi-centered, multi-stage process.The study investigates the timeline and context of horse domestication and the rise of widespread horse-based mobility in Eurasia. By analyzing 475 ancient horse genomes, the researchers found that reproductive control of modern domestic horses (DOM2) emerged around 2200 BCE through close-kin mating and shortened generation times. This marked the beginning of significant horse-based mobility, which coincided with a severe domestication bottleneck starting around 2700 BCE. The expansion of DOM2 horses across Eurasia ultimately replaced nearly every local horse lineage. The study also detected shortened generation times at the Botai settlement around 3500 BCE, suggesting local horse husbandry before the rise of modern domestic bloodlines. The findings challenge the common narrative of large horse herds accompanying steppe migrations around 3000 BCE and earlier, indicating that horse-based mobility developed much later. The research provides new insights into the genetic and demographic changes in horses during this period, supporting the idea that horse domestication was a multi-centered, multi-stage process.