Osage County, Oklahoma

From Wikipedia:

Most of the county is in the Osage Plains, and consists of open prairie. The eastern part of the county contains the Osage Hills, an extension of the Flint Hills in Kansas. Tallgrass Prairie Preserve is north of Pawhuska.

By the seventeenth century, the Osage had moved west of the Mississippi River and established themselves as a powerful nation in the areas of present-day Missouri and Arkansas between the Missouri and Red rivers, as well as extending to the west.  By 1760, they had increased their range to include the present Osage County.  Historically one of the most powerful Great Plains tribes, their numbers were reduced by infectious disease and warfare.In 1825, they ceded their claim to the land in present-day Oklahoma to the United States government in 1835.  In 1870, the Osage prepared for removal from Kansas, after having negotiated payment for their land. They purchased 1.57 million acres of their former territory from the Cherokee and, by owning it, had a stronger position in relation to the US government than did other tribes.

The Osage Agency was established at Deep Ford, later renamed as Pawhuska in 1872. It was named the county seat at statehood. The other chief settlements in the 1870s were Hominy and Fairfax, each of the three settled by a major Osage band.

In 1875 the land they purchased was designated the Osage Reservation and, because the tribe owned the land directly, they retained more control over their affairs than did tribes who only had rights to land held "in trust" by the United States government. This reservation became part of the Oklahoma Territory in 1890.  

In another important difference, as owners the Osage retained the communal mineral rights to their reservation lands. In October 1897, the Phoenix Oil Company drilled the first successful oil well on the Osage reservation and Oklahoma Territory. It was located along Butler Creek. In 1901, Phoenix Oil and Osage Oil companies combined their assets to form the Indian Territory Illuminating Oil Company (ITIO).

By 1920, the Osage were receiving lucrative revenues from royalties and were counted as the richest people in the country. During the 1920s, Osage County was the site of the infamous Osage Indian murders. 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.  To try to protect the Osage, Congress passed a law in 1925 prohibiting the inheritance of headrights by persons who were not at least half Osage in ancestry.