Mounds are generally regarded by Native Americans as holy places. They may contain human remains and associated artifacts, placed in accord with Native American ritual and belief systems. Boulder outlines were characteristic features of the Blood Run site. Over 100 of these were in the form of circles, approximately 30 feet in diameter, and ovals, approximately 60 feet long and 30 feet wide. They were probably placed around the lodges of site occupants.
None are visible today.
The Omaha appear to have been the principal occupants of Blood Run at the time of European contact. This may have been before the Omaha and Ponca separated. According to Omaha legend, the Arikara and Cheyenne were also present on the site at times. No documentation is found in historic records of the Yankton being at Blood Run until after the Omaha left. The time of most intensive occupation was probably during the late 1600s - early 1700s, at which time as many as 10,000 individuals may have simultaneously occupied the site, trading and interacting in social and ceremonial activities.