The phrase "Indian Territory" usually brings to mind the southeastern half of the present state of Oklahoma, one of the Twin Territories that were admitted to the Union as a single state in 1907.

Indian Territory actually existed under a formal Territorial Government for only a very brief time, but the phrase has also been used to describe many different regions down through the years as westward expansion changed the face of the Nation.  

Historically, the older term "Indian Country" is actually a more useful description.  If these maps appear crude, it's because they have been re-created from notes and sketches for a Term Project when I was in college many years BPC [Before Personal Computers].  I have made no attempt to track every encroachment and every land cession -- only to depict general boundaries as they existed at different times, with respect to present state lines.  More specific migration paths can be found in exploring the appropriate First Nation Histories and the individual land cessions that are covered on many state pages --  but I  believe this is enough to show how Tribes and Nations from such varied parts of the country ended up in what is now Oklahoma.  

 

Click on thumbnail map to see a larger version. 

	In the early 1700s, Britain controlled the eastern coast (shown in blue), while France held the Mississippi Valley (shown in olive green) and Spain had Florida and the Great Southwest (shown in yellow).  Only the British displaced the natives with their  settlements, so in this period everything that isn't blue was generally considered to be "Indian Country".
	At the Treaty of Paris in 1763, France ceded her land east of the Mississippi to England.    King George III issued the Indian Proclamation Line that ran along the crest of the Appalachian Mountains, creating the first official Indian Country.  It extended from the Appalachians to the Mississippi and south to the Spanish lands.
	The British then proceeded to negotiate treaties and acquire lands for future settlements.  By 1768 the Ft. Stanwix Treaty opened all lands south of the Ohio to the mouth of the Tennessee River.
	After the American Revolution, the new Treaty of Paris of 1783 officially revoked the Indian Proclamation Line, recognizing both intervening land cessions and the settlements that had already encroached across the Appalachians into the Ohio Valley.  Natural barriers, like the Ohio River, were again used as boundaries between white settlements and Indian Country.
	After the Louisiana Purchase in 1803, there was a movement to make the Mississippi River a natural barrier, with Indian Country to the west and everything east to be opened to settlement.  This map shows the logic of the proposed division.
	A period of rapid westward expansion followed and the line between white settlements and Indian Country was in a state of rapid flux.  By 1810 land cessions had extended west of the Mississippi.  Although they were not organized as a territory, by policy the western lands were reserved for resettlement of eastern tribes.
	The Indian Trade and Intercourse Act of 1834 created an Indian Territory (shown in red) that included all United States territory west of the Mississippi, except the states of Louisiana and Missouri and the Territory of Arkansas. It also included some areas east of the Mississippi in present-day Florida, Michigan, Wisconsin and Minnesota to which Indian Title had not been extinguished (these small isolates are not shown here).
	By 1854, Indian Territory covered only the area west of Arkansas and Missouri, from the Red River to the Missouri River, and west to the 100th Meridian. The Cherokee, Chickasaw, Choctaw, Creek, and Seminole occupied all of what is now Oklahoma, except the panhandle.  Others had been relocated to what would later become Kansas and Nebraska.
	After the Civil War, the Five Nations were forced to cede their western lands and tribes from the Great Plains were relocated there. By 1876, with the admission of Kansas and Nebraska to the Union, Indian Territory had shrunk to what is now the state of Oklahoma, excluding the panhandle.
	With the passage of the General Allotment Act and the creation of Oklahoma Territory, by 1889 Indian Territory had shrunk to its final form:  the Five Nations (Cherokee, Chickasaw, Choctaw, Creek and Seminole) and the Quapaw Tract.