The first European to reach Arkansas was the Spanish explorer Hernando de Soto at the end of the 16th century. Arkansas is one of several U.S. states formed from the territory purchased from Napoleon Bonaparte in the Louisiana Purchase. The early Spanish or French explorers of the state gave it its name, which is probably a phonetic spelling of the Illinois tribe's name for the Quapaw people, who lived downriver from them. Other Native American tribes who lived in Arkansas prior to westward movement were the Quapaw, Caddo, and Osage nations. In their forced move westward (under U.S. Indian removal policies), the Five Civilized Tribes inhabited Arkansas during its territorial period.