Question: The largest county in Oklahoma by area, gets its name from the broad rolling hills and rolling tallgrass prairie and Cross Timbers encompassing the county and surrounding areas, including portions of Mayes, Tulsa, Washington and Kay Counties, was created in what year?

full_context: Document 1: Seminole Nation of Oklahoma: The Seminole Nation of Oklahoma is a federally recognized Native American tribe based in the U.S. state of Oklahoma. It is the largest of the three federally recognized Seminole governments, which include the Seminole Tribe of Florida and the Miccosukee Tribe of Indians of Florida. Its members are descendants of the 3,000 Seminoles who were forcibly removed from Florida to Indian Territory, along with 800 Black Seminoles, after the Second Seminole War. The Seminole Nation of Oklahoma is headquartered in Wewoka within Seminole County, Oklahoma. Of 18,800 enrolled tribal members, 13,533 live within the state of Oklahoma. The tribe began to revive its government in 1936 under the Indian Reorganization Act. While its reservation was originally larger, today the tribal jurisdictional area covers Seminole County, Oklahoma, within which it has a variety of properties.
Document 2: Osage Hills: The Osage Hills is a hilly area in Oklahoma, commonly known as "The Osage". The name refers to the broad rolling hills and rolling tallgrass prairie and Cross Timbers encompassing Osage County and surrounding areas, including portions of Mayes, Tulsa, Washington and Kay Counties. The Osage is the southern extension of the Flint Hills of Kansas.
Document 3: Rainy Mountain: Rainy Mountain is a rounded hill standing northwest apart from the main Wichita Mountains in Kiowa County, Oklahoma. It was a prominent landmark for the Plains Indians on the southern plains.
Document 4: Pawhuska, Oklahoma: Pawhuska is a city in and the county seat of Osage County, Oklahoma, United States.
Document 5: Osage, Oklahoma: Osage is a town in Osage County, Oklahoma, United States. Also known as Osage City, it lies within the Osage Reservation on the shore of Lake Keystone. The population was 156 at the 2010 census, down 17 percent from 188 at the 2000 census.
Document 6: Southeast Kansas: Southeast Kansas is a region of the U.S. state of Kansas. It can be roughly defined by Woodson County in the northwest, Bourbon County in the northeast, Cherokee County in the southeast, and Montgomery County in the southwest. Geographically it is dominated by a broad rolling landscape located between the Flint Hills to the west and includes the Ozarks to the southeast. Some notable towns there include Pittsburg, Parsons, Coffeyville, Independence, Chanute, Fort Scott, and Iola. The region has a land area of 13,624.13 km² (5,260.30 sq mi) and a 2000 census population of 180,815 inhabitants. It has 6.43% of the state's land area and 6.726% of its population. It is dominated by a broad rolling landscape that includes the Ozarks. It receives more precipitation than any other part of Kansas. Southeast Kansas is located in the tallgrass prairie ecosystem of North America. Originally inhabited by several Native American tribes, frontier towns largely dependent on cattle ranching, and mining, were wracked by violence over the issue of slavery both before and during the American Civil War. Southeast Kansas offers one of the premier reconstructions of early life in the United States Army at Fort Scott National Historic Site.
Document 7: Osage County, Kansas: Osage County (county code OS) is a county located in the U.S. state of Kansas. As of the 2010 census, the county population was 16,295. Its county seat is Lyndon, and its most populous city is Osage City. The county was originally organized in 1855 as Weller County, and was renamed in 1859 after the Osage River that runs through it, which is itself named for the Osage Native American Tribe.
Document 8: Osage Plains: The Osage Plains are a physiographic section of the larger Central Lowland province, which in turn is part of the larger Interior Plains physiographic division. The area is sometimes called the Lower Plains, North Central Plains, and the Rolling Plains. The Osage Plains, covering west-central Missouri, the southeastern third of Kansas, most of central Oklahoma, and extending into north-central Texas, is the southernmost of three tallgrass prairie physiographic areas. It grades into savanna and woodland to the east and south, and into shorter mixed-grass prairie to the west. The Osage Plains consist of three subregions. The Osage Plains proper occupy the northeast segment. Although sharply demarcated from the Ozark uplift, the Plains are nonetheless a transitional area across which the boundary between prairie and woodland has shifted over time. In the central portion of the physiographic area lies the second subregion, the Flint Hills, commonly called "The Osage" in Oklahoma. This large remnant core of native tallgrass prairie is a rocky rolling terrain that run from north to south across Kansas and extends into Oklahoma. To the west and south of these hills are the Blackland Prairies and Cross Timbers. This vegetatively complex region of intermixed prairie and scrubby juniper-mesquite woodland extends into north-central Texas. Bluestem prairies and oak-dominated savannas and woodlands characterize the natural vegetation in the Cross Timbers. Much of the area has been converted to agriculture, although expanses of oak forest and woodland are still scattered throughout the eastern portion of the subregion.
Document 9: Tallgrass Prairie Preserve: The Tallgrass Prairie Preserve, located in Osage County, Oklahoma near Foraker, Oklahoma, is owned and managed by The Nature Conservancy. It is protected as the largest tract of remaining tallgrass prairie in the world. The preserve contains 39000 acre owned by the Conservancy and another 6000 acre leased in what was the original tallgrass region of the Great Plains that stretched from Texas to Manitoba.
Document 10: Osage County, Oklahoma: Osage County is the largest county by area in the state of Oklahoma in the United States. 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, Oklahoma, one of the first three towns established in the county. The total population of the county is 47,987.
Document 11: Osage Bank of Fairfax: The Osage Bank of Fairfax was the first bank building built in Osage County. It was built in 1904, at the time of the Oklahoma oil boom. It is one of four small bank buildings built in Richardsonian Romanesque style in Osage County, Oklahoma during 1904-1911. The others are Bank of Hominy, Bank of Burbank, and Bank of Bigheart.
Document 12: Cherokee Nation: The Cherokee Nation (Cherokee: ᏣᎳᎩᎯ ᎠᏰᎵ, "Tsalagihi Ayeli"), also known as the Cherokee Nation of Oklahoma, is the largest of three Cherokee federally recognized tribes in the United States. It was established in the 20th century and includes people descended from members of the Old Cherokee Nation who relocated from the Southeast due to increasing pressure to Indian Territory and Cherokee who were forced to relocate on the Trail of Tears. The tribe also includes descendants of Cherokee Freedmen and Natchez Nation. Over 299,862 people are enrolled in the Cherokee Nation, with 189,228 living within the state of Oklahoma. According to Bureau of Indian Affairs (BIA) head Larry EchoHawk, the Cherokee Nation is not the historical Cherokee tribe but instead a "successor in interest."
Document 13: McCurtain County, Oklahoma: McCurtain County is located in the southeastern corner of the U.S. state of Oklahoma. As of the 2010 census, the population was 33,151. Its county seat is Idabel. It was formed at statehood from part of the earlier Choctaw Nation in Indian Territory. The name honors an influential Choctaw family that lived in the area. Green McCurtain was the last chief when the Choctaw Nation was dissolved before Oklahoma became a state in 1907.
Document 14: Stillwater, Oklahoma: Stillwater is a city in north east Oklahoma at the intersection of US-177 and State Highway 51. It is the county seat of Payne County, Oklahoma, United States. As of 2012, the city population was estimated to be 46,560, making it the tenth largest city in Oklahoma. Stillwater is the principal city of the Stillwater Micropolitan Statistical Area which had a population of 78,399 according to the 2012 census estimate. Stillwater was part of the first Oklahoma Land Run held April 22, 1889, when the Unassigned Lands were opened for settlement and became the core of the new Oklahoma Territory. The city charter was adopted on August 24 later that year. Stillwater is home to the main campus of Oklahoma State University, as well as a branch of Northern Oklahoma College, Meridian Technology Center, and the Oklahoma Department of Career and Technology Education.
Document 15: Osage State Fishing Lake: Osage State Fishing Lake is located in northern Osage County, Kansas. It is a mile east of US 75. Scranton, Kansas, is to the lake's northwest and Overbrook, Kansas, is to the northeast. Osage Lake is a freshwater man-made lake, constructed in 1955. It has a surface area of 140 acres, The parkland in which the lake is contained has 366 acreas of land, mostly tall grass prairie with numerous wooded areas. The lake is owned by the State of Kansas.
ground_truth: 1907