What influenced the way of life for both northwest coast Indians and plateau Indians?

Indigenous peoples of the Northwest Plateau, also referred to by the phrase Indigenous peoples of the Plateau, and historically called the Plateau Indians (though comprising many groups) are indigenous peoples of the Interior of British Columbia, Canada, and the non-coastal regions of the Northwestern United State

Yakama woman, photographed by Edward Curtis

Their territories are located in the inland portions of the basins of the Columbia and Fraser Rivers. These tribes mainly live in parts of the Central and Southern Interior of British Columbia, northern Idaho, western Montana, eastern Washington, eastern Oregon, and northeastern California. The eastern flank of the Cascade Range lies within the territory of the Plateau peoples.[1]

There are several distinguishing features that differentiate plateau culture from the surrounding native cultures. These include a high reliance on roots, such as biscuitroot and camas, as a food source, a high reliance on short duration salmon and eel runs, and long-term habitation of winter villages at fixed locations along rivers or lakes. There was a lack of social stratification and a lack of tribal organization beyond the village level.