Where do wild mustangs come from?

Wild mustangs trace their ancestry to the horses brought to North America by Spanish conquistadors beginning in the early 1500s, with some of the most historically significant introductions coming through Hernán Cortés's expedition to Mexico in 1519 and subsequent Spanish settlement throughout the American Southwest. These horses — primarily of Iberian breeding, including Andalusian and Barb bloodlines — were periodically lost, stolen by Native American tribes, or deliberately released, and over the following centuries they spread across the continent and established free-roaming herds in the grasslands and rangelands of the West. The horse's reintroduction to North America after an absence of approximately ten thousand years transformed the cultures of Plains Indian tribes and the practicalities of western settlement, creating the foundation for the cattle ranching industry and the western riding tradition. Over the centuries following the original Spanish introductions, mustang herds were further influenced by escaped or released domestic horses of various breeds — including quarter horses, draft breeds, and thoroughbreds — which is why contemporary mustang herds vary considerably in size, conformation, and temperament from one region to another. The herd management areas overseen by the Bureau of Land Management today contain an estimated sixty thousand to eighty thousand horses at any given time, with population numbers fluctuating based on birth rates, adoption activity, and management decisions about gather operations. Certain herds carry reputations for specific qualities — the Kiger mustangs of Oregon are celebrated for their Spanish colonial conformation, the Pryor Mountain horses of Montana and Wyoming for their documented historical bloodlines — while other herds reflect the eclectic mix of domestic influences accumulated over generations.