yes
Oklahoma.
The Oklahoma territory
It was a territory until it became a US State in 1907.
The answer is Oklahoma*
Though not always considered a Southwest state, the eastern half of Oklahoma was known as Indian Territory from 1834 to 1907, when it was joined with the Oklahoma Territory.
Oklahoma
Since November 16, 1907. Prior to then, it was the Oklahoma Territory.
It was Oklahoma.
Oklahoma
Oklahoma Territory
None, when the United States admitted Oklahoma as a state in 1907, all titles to "Indian Territory" were extinguished (the treaty was violated).