What role did geography play in the alignment of Indian territory with the south in the civil war?

Geography played a key role in aligning Indian territory with the South in the Civil War due to the region's proximity to Confederate states and the presence of alliances and treaties between Native American tribes and the Confederate government. The Choctaw, Chickasaw, Cherokee, Creek, and Seminole nations in Indian Territory had historical ties with the South and thus chose to support the Confederacy during the war.