The territory would be “set apart for the absolute and undisturbed use and occupation” of the Sioux Nation.

Those words — absolute and undisturbed — were not rhetorical flourish.

They were the terms of the agreement.

Article 12 added a further protection that would become the crux of the legal dispute a century later.

It provided that no cession of any part of the reservation — no agreement by which the Sioux would give up any portion of their territory — would be valid or binding “as against the said Indians unless executed and signed by at least three-fourths of all the adult male Indians occupying or interested in the same.”

Three-fourths.