In 1686, the French established the first white settlement in Arkansas. In 1803, Arkansas was sold to the United States as part of the Louisiana Purchase. In 1836, it became the 25th state in the Union. European Exploration and Early Settlement 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 reached it 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. The entire Mississippi River valley, which includes Arkansas, was claimed for France in 1682 by René-Robert Cavelier, Sieur de La Salle. He called the claim Louisiana, in honor of King Louis XIV. In 1686, Henri Tonti built a camp at the mouth of the Arkansas River. Arkansas’ first permanent white settlement, Arkansas Post, was founded near there. To develop that vast Louisiana territory, France gave control of the area to the Western Company. The Western Company brought several hundred colonists to Arkansas. However, the effort was largely unsuccessful, and many of the colonists left. Spain gained ownership of France’s lands west of the Mississippi in 1763. France took the land back in 1800. Then, in 1803, the area was sold to the United States in a transaction known as the Louisiana Purchase. The Louisiana Purchase added 827,987 square miles of land to the U.S. for a cost of just $15 million.