Prior to 1820, North Park was a favorite summer hunting ground for several Native American tribes, especially the Utes and Arapaho, as well as the Crow, Sioux, and Cheyenne. These early native people were drawn there in large part by the abundance of big game, including bison, elk, bighorn sheep, deer, and pronghorn antelope. Evidence of early American Indian presence still remains in North Park in the form of well-worn trails, tepee rings, and burial trees. The Utes called North Park the "Bull Pen" and the "Cow Lodge" because the broad valley is surrounded by a circle of mountain ranges, creating an enormous pen.