Why did the first nations of the plains need portable teepees?

Tipi's were used for shelter by the Plains Indian tribes such as the Blackfoot, Crow, Sarsi, Hidatsa, Omaha, Comanche, Teton-Dakota, Assiniboin, Cheyenne, Gros Ventre, Arapaho, Kiowa, Plains-Cree, Mandan, and Pawnee.

Tipi's were easily moved, were warm in the winter and cool in the summer, and the opening at the top allowed the use of a fire inside the tipi.