Why did Native Americans live in teepees?  

  Tipis were warm in winter, cool in summer. A tipi's shape protected it from the Plains winds. Tipis were easy to move (and fitted the nomadic lifestyle). Tipis were circular, and Native Americans thought that: "...the power of the world works in circles". Tipi dwellers believed that a fixed home was unhealthy - a cage - while a tipi was healthy.