The negotiations had been preceded by years of armed conflict — most significantly, what became known as Red Cloud’s War, in which Lakota and allied warriors had successfully resisted the construction of the Bozeman Trail through their hunting territories, eventually forcing the United States to abandon forts it had built and to negotiate on terms substantially more favorable to the Sioux than those the government had initially offered.

Red Cloud’s War was, in the historical record, one of the few instances in which the United States military was compelled to withdraw from contested territory by sustained armed resistance from a Native nation.

The Fort Laramie Treaty of 1868 was, in part, the documentation of that outcome.

The treaty’s central provision, as it applied to the Black Hills, was Article 2.

It established what the treaty called the Great Sioux Reservation — a vast territory encompassing all of present-day South Dakota west of the Missouri River.

The language was precise.