Tipi ring

Tipi rings are circular patterns of stones left from an encampment of Post-Archaic, protohistoric and historic Native Americans.

The rings of stone held down the edges of animal skin hides of the cone-shaped tipis, to keep them snug against the ground.

[2][3] Stones were replaced by wooden pegs to hold down the tents after the introduction of axes by people of European ancestry.

"[4] From a study of 137 sites on the 2,000-square-mile (5,200 km2) Blackfeet Indian Reservation, tipis were often arranged in a pattern, such as a single or double row, semi-circle, circle, triangle, V-shape or a haphazard shape.

[6] Between Green River, Wyoming and Denver, Colorado, a 300 miles (480 km) long corridor, there are 136 tipi ring sites.