Tipis and hogans are very specific structures. The tipi is, traditionally, buffalo skin over a conic structure of long poles, very portable. It evolved from a less substantial structure with the introduction of the horse to the plains culture. Prior to the introduction of the horse the main pack animal was the dog.

The hogan is a permanent structure of log and mud, still used today as the primary housing for many Navajo on the reservation. I visited one once. It's the only time I have ever seen a gas refrigerator in use.