google Johnny Arlee he has written some books about the Salish. what other western MT tribes?

To start out with, I'd recommend picking up a copy of the Smithsonian's Handbook of North American Indians, Vol. 12: Plateau. That will give you a basic introduction as well as pointing you in the direction of other resources to explore.

In the Handbook, the séliš (from which English gets the words Selish and later the modern Salish) are generally referred to as the Flathead to avoid confusion with the larger Salish identity.