Spanish conquistadors came to the Americas in the early 1500s, bringing with them both domesticated horses and cattle to help them conquer the vast new world. The journey over the seas was often a grueling one for man and beast alike. The horse would become a central factor in the settlement of the Western Hemisphere. The Spanish also brought cattle that became the foundation stock for the great cattle industry that was to develop extensively during the 19th century. Once the conquistadors destroyed the Aztecs and other Indian peoples, many Spanish horses escaped or were turned loose and became feral or wild. The Spanish horses, which we now describe as Andalusians, were from the finest strains and were regarded as the foremost breed in Europe. They formed the nucleus of the great herds of wild horses that spread upward from Mexico into the United States and the western plains country.

"Although North America was once home to boundless herds of wild horses, a combination of man, a changing environment and disease forced them to emigrate from this continent."

The North American Indians' astonishment at these "horse-men" contributed to their submission to the conquistadors. Bernal Diaz del Castillo, who accompanied Cortes in his 1519 incursion into Mexico, wrote "The natives had never seen horses up to this time and thought the horse and rider were all one animal. " But over time, the Mexican Indians became the original cowboys. Enslaved by Spanish conquerors who put them to work tending herds on their vast rancheros, the Indians became highly skilled horseman, developing a close bond with this magnificent creature and the beginning America's long romance with wild horses.