On June 15, 1836, Arkansas was admitted as the 25th state of the Union. Indians had lived in Arkansas as early as 10,000 B.C. When the first European explorers arrived, they found three main tribes in the area: the Caddo, Osage, and Quapaw. Hernando de Soto of Spain was the first European to reach the Mississippi River. He arrived in 1541, near what is now Memphis, Tennessee. He then crossed Arkansas and reached the Ozark Mountains. In 1673, Father Jacques Marquette and Louis Jolliet traveled down the Mississippi to the mouth of the Arkansas River. René-Robert Cavelier, Sieur de La Salle, claimed the entire Mississippi River valley, which includes Arkansas, for France in 1682. He called the claim Louisiana, in honor of King Louis XIV.