The Nez Perce tribe has been breeding the Apaloosa horse
since the 1700's. According to this article:
http://en.wikipedia.org/wiki/Appaloosa

"It is unclear how spotted horses arrived in the Americas, although the Spanish Conquistadors may have brought some vividly marked horses with them when they first arrived in the early 1500s. One horse with snowflake patterning was listed with the 16 horses brought to Mexico by Cortez. Additional spotted horses were noted by Spanish writers in 1604. Additional numbers arrived when spotted horses went out of style in late-18th century Europe, resulting in large numbers shipped to the west coast of America and traded to Spanish settlers and the Indian people of the Pacific Northwest, a voyage survived only by the hardiest animals.

Horses reached the Pacific Northwest by 1700. The Nez Perce people, who lived in what today is eastern Washington and Oregon, obtained horses from the Shoshone people circa 1730, and from there took advantage of the fact that they lived in excellent horse-breeding country, relatively safe from the raids of other tribes, and developed strict breeding selection practices for their animals. They were one of the few tribes to actively use the practice of gelding inferior male horses, and actively traded away poorer stock to remove unsuitable animals from the gene pool, and became known as notable horse breeders by the early 1800s."

This tribe lived and lives in and around the Palouse Hills and the Palouse river. ...Gradually, the name evolved into "Appaloosa."