The earliest inhabitants of what is now South Dakota were prehistoric hunters who reached the area perhaps 15,000 years ago. By 500 A.D., they had been succeeded by the Mound Builders. Arikara Indians reached South Dakota from Kansas and Nebraska about the 16th century. Then came the Sioux (Dakota) Indians, who moved westward from Minnesota beginning in the 17th century. The Sioux had spread throughout the region by the time the first white explorers arrived.

Important dates in South Dakota
1682 Rene-Robert Cavelier, Sieur de La Salle, claimed for France all the land drained by the Mississippi River. This land included the South Dakota region.
1743 Francois La Verendrye and Louis-Joseph La Verendrye were the first white people known to visit the South Dakota region.
1803 The United States acquired South Dakota through the Louisiana Purchase.
1804, 1806 Meriwether Lewis and William Clark passed through South Dakota on their expedition to and from the Pacific Ocean.
1817 Joseph La Framboise established the first permanent settlement in South Dakota at what is now Fort Pierre.
1861 The U.S. Congress created the Dakota Territory.
1868 The Treaty of Fort Laramie ended Red Cloud's War.
1874 Gold was discovered in the Black Hills.
1889 South Dakota became the 40th state of the United States on November 2.
1927 Gutzon Borglum began work on Mount Rushmore National Memorial. The monument was completed in 1941.
1930's South Dakota suffered its worst drought.
1944 Congress authorized construction of Fort Randall, Oahe, Gavins Point, and Big Bend dams.
1973 A group of armed Indians seized the village of Wounded Knee and occupied it for 71 days.
1980 The U.S. Supreme Court ordered the federal government to pay South Dakota Indian tribes $105 million for land seized by the government in 1877.
1989 Legalized gambling began in Deadwood.
2001 The Homestake gold mine closed.