Cayuse Tribe - http://en.wikipedia.org/wiki/Cayuse

Cayuse pony/horse breed -
http://www.ansi.okstate.edu/breeds/horses/cayuseindian/
These horses are related to Appaloosa, Pinto and Paint horses.

Palouse hills...close to this area
http://en.wikipedia.org/wiki/Palouse

neighboring tribe - http://en.wikipedia.org/wiki/Palus_(tribe)
related to these tribes...Wenatchi, Okanagan, Nez Perce

possibly the originator of the http://en.wikipedia.org/wiki/Appaloosa
appaloosa horse.

the natives of this area were well known for their horse breeding
and training expertise.