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?
Sentence (from "Osage County, Oklahoma"): The county is coextensive with the Osage Nation Reservation, established by treaty in the 19th century when the Osage relocated there from Kansas.
Relevant evidence: No