The Flint Hills, historically known as Bluestem Pastures or Blue Stem Hills, are a region of hills and prairies that lie mostly in eastern Kansas. It is named for the abundant residual flint eroded from the bedrock that lies near or at the surface. It consists of a band of hills extending from Marshall and Washington Counties in the north to Cowley County, Kansas and Kay and Osage Counties in Oklahoma in the south, to Geary and Shawnee Counties west to east. Oklahomans generally refer to the same geologic formation as the Osage Hills or "the Osage."

Osage County is the largest county by area in the U.S. state of Oklahoma. Created in 1907 when Oklahoma was admitted as a state, the county is named for and is home to the federally recognized Osage Nation. The county is coextensive with the Osage Nation Reservation, established by treaty in the 19th century when the Osage relocated there from Kansas. The county seat is in Pawhuska, one of the first three towns established in the county. The total population of the county as of 2020 was 45,818.