Osage Indians, a tribe of the Siouan linguistic stock, and most important of the Dhegiha group, which included also the Omaha, Ponca, Kansa, and Quapaw. The Osage lived mainly along the Osage River (southwestern Missouri). They were a warlike people, often fighting with neighboring tribes. The Osage had early contacts with French, Spanish, and English explorers, and by the early 18th century had formed a strong alliance with the French.

In ceding lands to the United States government, 1808–70, the Osages made profitable deals. Grazing leases added to their funds, and they were known as the richest tribe in the United States even before oil was discovered on their reservation (Osage County, Oklahoma). In 1906, they divided up their land among the members of the tribe, each receiving an equal share.