Kyaiyesisahtai

Kyaiyesisahtai, the Marias River, flows eastward from the Rocky Mountain front to join the Missouri. The Blackfoot name means Bear River. Its tributaries drain the high country to the west before meeting in the plains, and its valley crosses a landscape long associated with Blackfoot peoples. In 1805 Lewis and Clark encountered the river at its junction with the Missouri and had to determine which stream led onward toward the mountains.