High Quality Content by WIKIPEDIA articles! During the American Civil War, Indian Territory occupied most of what is now the U.S. state of Oklahoma and served as an unorganized region set aside for Native American tribes of the Southeastern United States; they had been removed from their lands. The area was the scene of numerous skirmishes and seven officially recognized battles involving Native American units allied with the Confederate States of America, Native Americans loyal to the United States government, and Union and Confederate troops.