The Appaloosa is a horse bree known for its preferred leopard-spotted coat pattern and other distinctive physical characteristics. While there is evidence of leopard-spotted horses dating back to the Paleolithic era in Europe, the Nez Perce people of the American Pacific Northwest developed the American breed. They were once referred to by white settlers as the "Palouse horse", possibly after the Palouse River, which ran through the heart of Nez Perce country. Gradually, the name evolved into "Appaloosa". The Nez Perce people lost most of their horses following the end of the Nez Perce War in 1877 and the breed fell into decline for several decades. However, a small number of dedicated breeders kept the Appaloosa alive for several decades until a registry was formed in 1938. Today the Appaloosa is one of the most popular breeds in the United States, and it was named the official state horse of Idaho in 1975.