The name "Appalousa" may have originated from the Palouse, a tribe of Native Americans that lived in the Great Plains and Rocky Mountains region and ranged from the Rocky Mountains and Black Hills of what is now North Dakota and South Dakota to the Rocky Mountain states of Utah, Colorado, and New Mexico. The tribe was first mentioned by the Lewis and Clark Expedition in 1804. The Appaloosa horse breed may have been named after these Native American people, but there isn't any evidence to support the theory.
The term "Appaloosa" was first coined by the French explorer Étienne Marchand, who visited the area in 1811 and discovered the Appaloosa horses in the Nez Perce Indian tribe.
The Appaloosa horse breed is now recognized as one of the oldest breeds in North America, pre-dating the now more common breeds such as the Quarter Horse. The breed was originally developed by the Nez Perce people of Idaho and Oregon as a general-purpose horse for hunting and war.