In the 18th century, pressured by the Ojibwe and Cree peoples (the Iron Confederacy), who had earlier and better access to guns through the fur trade, the Crow had migrated to this area from the Ohio Eastern Woodland area of present-day Ohio, settling south of Lake Winnipeg. From there, they were pushed to the west by the Cheyenne. Both the Crow and the Cheyenne were pushed farther west by the Lakota, who took over the territory west of the Missouri River, reaching past the Black Hills of South Dakota to the Big Horn Mountains of Wyoming and Montana. The Cheyenne eventually became allies of the Lakota, as they sought to expel European Americans from the area. The Crow remained bitter enemies of both the Sioux and Cheyenne. The Crow managed to retain a large reservation of more than 9300 km2 despite territorial losses.