The Pryor Mountain mustang is a substrain of mustang considered to be genetically unique and one of the few strains of horses verified by DNA analysis to be descended from the original Colonial Spanish horses brought to the Americas by the Spanish. They live on the Pryor Mountains Wild Horse Range located in the Pryor Mountains of Montana and Wyoming in the United States, and are the only mustang herd remaining in Montana, and one of sixteen in Wyoming. They are protected by the Wild and Free-Roaming Horses and Burros Act of 1971 (WFRHBA) and managed by the Bureau of Land Management (BLM), who has set the optimum herd number at 120 animals. Genetic studies have revealed that the herd exhibits a high degree of genetic diversity and a low degree of inbreeding, and BLM has acknowledged the ge