The Native Americans that lived along the Missouri had access to ample food , water , and shelter . Many migratory animals inhabited the plains at the time , providing them meat , clothing , and other everyday items ; there was also great riparian areas in the river 's floodplain that provided them with natural herbs and staple foods . No written records from the tribes and peoples of the pre @-@ European period exist because they did not use writing . According to the writings of explorers , some of the major tribes along the Missouri River included the Otoe , Missouria , Omaha , Ponca , Brulé , Lakota , Sioux , Arikara , Hidatsa , Mandan , Assiniboine , Gros Ventres and Blackfeet .