A gefen yammacin yankin, yankin ya hada da yawancin yankin gabashin Utah, wanda Ute da Shoshoni ke da iko sosai. Yankin Gabas ya kasance da yawa daga Cheyenne da Arapaho, da kuma Pawnee, Comanche da Kiowa. A cikin 1861, kwanaki goma kafin kafa yankin, Arapaho da Cheyenne sun yarda da Amurka su ba da mafi yawan yankunansu na filayen zuwa fararen fata amma an yarda su zauna a yankunansu mafi girma, don haka za su iya jurewa da dindindin.
Yankin yammacin Kansas Territory, da kuma wasu daga yankin kudu maso yammacin Nebraska, da kuma karamin yanki na arewa maso gabashin New Mexico Territory