I recently read two books by Finnish historian Pekka Hamalainen covering the histories and life styles of native Americans. Both "Comanche Empire" and "Lakota America" examined tribes that were living on the great plains and subsisted almost entirely on buffalo meat.

A lot of the warfare and raiding characteristic of those tribes was done in the interest of obtaining carbohydrates in the form of corn, beans, and squash that were grown by tribes that had settled along rivers and in valleys. The buffalo only diet was not enough to keep them healthy.