There is archeological evidence that Indians inhabited what is now Wyoming as early as 11,000 B.C. About 6,000 years ago, the region became a desert, and most of the occupants left. Around 2500 B.C., the climate improved and some Indians returned. They lived mainly by foraging. About 500 A.D., the buffalo became important to the Indians, as a source of food, clothing, and skins for trade. The Indians remained the sole inhabitants of Wyoming until the 19th century. The major tribes at that time were the Shoshoni in the west, the Crow in the north, and the Cheyenne and Arapaho in the southwest.

Important dates in Wyoming
1807 John Colter explored the Yellowstone area.
1812 Robert Stuart discovered South Pass across the Rocky Mountains.
1833 Captain Benjamin L. E. de Bonneville mapped the Wyoming area and discovered oil east of the Wind River Mountains.
1834 William Sublette and Robert Campbell established Fort William (later Fort Laramie).
1843 Scout Jim Bridger established Fort Bridger.
1867 The Union Pacific Railroad entered Wyoming.
1868 Congress created the Territory of Wyoming. Its first coal mines began operation in Carbon and Sweetwater counties.
1869 The Wyoming territorial legislature gave women the right to vote and hold elective office.
1872 Yellowstone became the first national park.
1883 Wyoming's first oil well was drilled in the Dallas Field.
1890 Wyoming became the 44th state on July 10.
1892 The Johnson County War broke out after a dispute over cattle rustling.
1906 President Theodore Roosevelt made Devils Tower the first national monument.
1910 Engineers completed Shoshone (now Buffalo Bill) Dam.
1925 Nellie Tayloe Ross became the first woman governor in the United States.
1929 Grand Teton became a national park.
1938-1939 Engineers completed Alcova and Seminoe dams.
1951-1952 Major uranium deposits were found in several parts of Wyoming.
1960 The nation's first operational intercontinental ballistic missile base opened near Cheyenne.
1965 Minuteman missile installations were completed near Cheyenne.
1988 Fires damaged large areas of Yellowstone National Park.