 Conflicts between natives and settlers over the opening of the Bozeman Trail in the Dakotas , Wyoming and Montana led to Red Cloud 's War , in which the Lakota and Cheyenne fought against the U.S. Army . The fighting resulted in a complete Native American victory . In 1868 , the Treaty of Fort <unk> was signed , which " guaranteed " the use of the Black Hills , <unk> River Country and other regions surrounding the northern Missouri River to Native Americans without white intervention . The Missouri River was also a significant landmark as it divides northeastern Kansas from western Missouri ; pro @-@ slavery forces from Missouri would cross the river into Kansas and spark <unk> during Bleeding Kansas , leading to continued tension and hostility even today between Kansas and Missouri . Another significant military engagement on the Missouri River during this period was the 1861 Battle of <unk> , which did not affect Native Americans but rather was a turning point in the American Civil War that allowed the Union to seize control of transport on the river , <unk> the state of Missouri from joining the Confederacy . 
