The Sioux lived in tepees, tents made of animal skins or birch bark and long, wooden support poles. The tepee was a shelter that kept warm in the winter, cool in the summer, and dry thunderstorms. The tepee was easily and deconstructed, which made it advantageous when following buffalo herds hundreds of miles the Great Plains. The tepee was also designed to its inhabitants to light indoor fires. Sioux tepees were built with two smoke flaps at the top, which could be with poles to the wind from blowing inside the .