Created in 1907 when Oklahoma was admitted as a state, the county is named for and is home to the federally recognized Osage Nation.

[1] During the 17th century, the Osage and other Dhegihan Siouan tribes were displaced westward from the Ohio Country following the Beaver Wars.

Historically one of the most powerful Great Plains tribes, their numbers were reduced by infectious disease and warfare after encounter with Europeans.

In 1825, they ceded their claim to the land in present-day Oklahoma to the United States government, which included it in a "perpetual outlet to the west given to the Cherokee Nation by the Treaty of New Echota" in 1835.

[4] As owners, the Osage negotiated the retention of the communal mineral rights to their reservation lands.

It arranged with the Bureau of Indian Affairs to sub-lease the eastern part of the Osage reservation until 1916.

[3] All subsurface minerals, including oil, are owned by the Osage Nation and held in trust for them by the Federal Government.

Each mineral lease was negotiated by the Osage National Council and approved by the U.S. Secretary of the Interior.

Later the enrolled Osage and their descendants received oil and other mineral royalties as payments based on these "headrights".

[5] By 1920, the Osage were receiving lucrative revenues from royalties and were counted as the richest people in the country.

Because of the great wealth being generated by oil, an estimated 60 tribal members were killed as whites tried to gain their headrights, royalties or land.

The FBI believed that several white husbands of Osage women had committed or ordered murders of their wives.

Congress had passed a law in 1921 requiring all Osage of half or more Indian ancestry to have a guardian appointed by the court until the person proved to be "competent."

There was extensive corruption as such guardians manipulated people to give or bequeath land to them in order to get access to oil rights.

Three other counties, Thurston in Nebraska; and Dewey and Ziebach in South Dakota, lie entirely in parts of two separate Indian reservations.

As of the 2010 United States census,[17] there were 47,472 people, 18,205 households, and 12,972 families residing in the county.

Elementary only: Former districts: The following sites in Osage County are listed on the National Register of Historic Places: Osage County is the setting of Oklahoma native Tracy Letts's play August: Osage County (2007), which won the Pulitzer Prize for Drama and a Tony Award in 2008, and the 2013 movie adaptation of the same name which stars Meryl Streep.

Filming took place in rural Osage County, including Pawhuska, Barnsdall and Bartlesville.

[22] Killers of the Flower Moon, the 2023 film directed by Martin Scorsese, centers on a series of Oklahoma murders in the Osage Nation during the 1920s.