A specialized subsistence pattern in which horses are used extensively in hunting large game animals. Equestrian foragers evolved in only two areas of the world--the great plains of north america and the sparse grasslands of southern argentina. In both cases, pedestrian foragers acquired horses from spanish settlers in the early 17th century. Over several generations, horse breeding and riding skills were honed. This resulted in a revolutionary change in these native american societies. The horse became the principle mode of transportation and dramatically increased hunting success in the pursuit of large animals. These societies became larger, more mobile, and were now able to travel over larger areas throughout the year. Horses allowed them to effectively follow the seasonal migrations of large herbivores over hundreds of miles. In north american the prey of choice was the bison and in south america it was the guanaco. ("equestrian" is derived from the latin word equus meaning horse. )