Oklahoma Territory began with the Indian Intercourse Act of 1834 when the United States Congress set aside land for Native Americans. At the time, the land was unorganized territory that consisted of the federal land "west of the Mississippi and not within the states of Missouri and Louisiana, or the territory of Arkansas..." By 1856, the territory had been reduced to approximately the modern-day borders of the state of Oklahoma, except for the Oklahoma Panhandle and Old Greer County. These lands became known as Indian Territory, as they had been granted to certain Indian nations under the Indian Removal Act, in exchange for their historic territories east of the Mississippi River.