Northern Plains tribes conducted communal autumn buffalo hunts to secure meat and hides for food, shelter, clothing, and other needs before the harshest winter weather, since hunting on foot during severe winter conditions would have been nearly impossible. For 300 years, from 1500 to 1800 A.D., various Plains Indian tribes repeatedly used this natural sinkhole as a trap to kill buffalo. Excavations suggest that 10,000 or more buffalo were killed here in 25 to 30 hunts, and that five or more tribes used this site during that period. These communal hunts likely required the coordinated efforts of several hundred people in three stages: gathering and driving the herd to the kill site, skinning and butchering in the sinkhole, and processing the meat and hides in a nearby camp. Most of this work was done on foot, with dogs used as beasts of burden, because horses were not acquired by Indians in this region until the late 1700s.