Although many European and European-American migrants to western North America had previously passed through the Great Plains on the Oregon and Santa Fe Trails, the California gold rush greatly increased traffic. The United States government undertook negotiations with the Native American Plains tribes living between the Arkansas and Missouri Rivers to ensure protected right-of-way for the migrants. The Fort Laramie Treaty of 1851 was signed on September 17 between United States treaty commissioners and representatives of the Cheyenne, Sioux, Arapaho, Crow, Assiniboine, Mandan, Hidatsa, and Arikara nations. The treaty sets forth traditional territorial claims of the tribes as among themselves.^[2] The Indians guaranteed safe passage for settlers on the Oregon Trail in return for promises of an annuity in the amount of fifty thousand dollars for fifty years. The Native American nations also allowed roads and forts to be built in their territories.

• http://en.wikipedia.org/wiki/Treaty of Fort Laramie (1851)