The Colonial Spanish Horse developed from animals first brought from the Iberian peninsula to the Americas during the conquest and establishment of the Spanish colony of New Spain in what today is Mexico. As the conquest of Mexico progressed during the 16th century, horse herds spread north and crossed the Rio Grande. Over the next one hundred years, horses in the Americas were stolen and traded by the Apache, Comanche, and later the Utes and Shoshone to various tribes across the Great Plains and Rocky Mountains.
On the brink of extinction in the early part of this century, the Spanish Mustang is one of the first breeds developed from a planned conservation program to save the descendants of these Spanish horses. This effort is mostly attributed to Robert E. Brislawn of Oshoto, Wyoming, and his brother Ferdinand L. Brislawn of Gusher, Utah. Credit for the preservation effort also goes to Gilbert Jones and Ilo Belsky. They gathered horses from feral Mustang herds, Native American herds and ranch stock from throughout the west, chosen because they had a phenotype that indicates Spanish ancestry. Two full brothers, Buckshot and Ute, were among the first foundation stallions, sired by a buckskin stallion named Monty and out of Ute Reservation blood on the dam’s side. Monty, captured in 1927 in Utah, escaped back to the wild in 1944, taking his mares with him. He was never recaptured.