tipi ring

 A circle of stones on the ground marking where a tipi once stood — the rocks that held down the edges of the hide cover, left in place after the structure was taken down and the people moved on. Tipi rings are found across the Great Plains by the thousands, sometimes clustered in groups that indicate seasonal camps used repeatedly over generations. They are among the most understated and moving marks on the American landscape — just a ring of stones in the grass, and a whole way of life implied.