The site is considered sacred after the unprovoked assault on an encampment of approximately 750 Native people resulted in the murder of hundreds of men, women and children.

of the Interior BLM, Colorado Historical Society and accompanied by Native American observers, made a major archaeological discovery of remains of the massacre site.

The law authorized establishment of the site once the National Park Service acquired sufficient land from willing sellers to preserve, commemorate, and interpret the massacre.

[8] The expansion of the site contributed to one of the most intact shortgrass prairie ecosystems within the National Park system, providing habitat for a wide range of plants, wildlife and species of special concern.

On September 9, 2006, the Cheyenne and Arapaho Tribes of Oklahoma conveyed to the United States title to 1,465 acres (6 km2) to be held in trust for the National Historic Site.