The farm I grew up on had teepee rings in the pasture. We had no idea how old they were, or which native tribes had made them. I've read the Three Affiliated Tribes from the area (the combined tribes of the Hidatsa, the Mandan, and the Arikara) have said the rings were there before they came to the land.
Some call them "stone circles," used for ceremonial purposes, believing that the local natives used pegs instead of rocks to hold down the edges of their teepee (or tipi) skins.
But I like the explanation of the Crow translation of "prehistory"--"biiaakashissihipee" literally means "when we used stones to weigh down our lodges."
The majority of the natives in that area built earth lodges for permanent homes, rather than being nomadic hunters. Some think these rings were made for summer use of hunting. That would make sense in our pastures, since they are perched on the top of the coulees with excellent lookouts in each direction. (If winter dwellings, it seems like they would have chosen areas out of the cold winds.) Another sign that they were used in the summer, was that none of these have the winter inner circle fire pits. In the summer, they built fires outside the teepees.
Above, our daughter Jana standing in the middle of a larger teepee ring, and below, at the edge of a smaller one.
Warming her hands by the (possible) fire pit.
Relaxing after a hard day on the hunt.