The Atsina, also known as the Gros Ventre or White Clay People, are a Plains tribe. They once belonged to an Algonquian parent tribe that included the Arapaho. In the late seventeenth or early eighteenth century, the Atsina broke off from the Arapaho and moved northward and westward to the Eagle Hills in Saskatchewan. Historians are not entirely sure why.
In the middle of the eighteenth century, the Atsina acquired horses and became equestrian buffalo hunters. In the late eighteenth century, the Cree and Assiniboine pushed the Atsina from Saskatchewan southwest to the Upper Missouri River.
In 1861, the Atsina sought an alliance with their erstwhile enemies, the Crow. At some point in the mid-nineteenth century, the Atsina allied with their former enemies, the Assiniboine, to resist the encroachments of the Sioux into their hunting territory. In the second half of the nineteenth century, the territory under the control of the Atsina steadily eroded. An executive order by President Ulysses S. Grant in 1873 established a large reservation for the Blackfoot, Assiniboine, and Atsina in northern Montana. In January, 1887, representatives of the federal government met with the Atsina and Assiniboine at the Fort Belknap Agency to negotiate the cession of most of the Indians’ reserve. President Grover Cleveland signed the Fort Belknap agreement into law on May 1, 1888, reducing the Atsina and Assiniboine to a shared reservation of approximately 600,000 acres. Despite the diminution of their territory, the Atsina and Assiniboine of the Fort Belknap Reservation won an important United States Supreme Court decision in the early twentieth century that became a landmark in American Indian law. On January 6, 1908, the Supreme Court ruled in Winters v. United States that the Indians of Fort Belknap Reservation, rather than nearby white settlers, had first rights to the contested water of the Milk River.
In 1934, Fort Belknap became the first reservation in the Plains to establish a government under the auspices of the Indian Reorganization Act. For the Atsina, reorganization had the unanticipated consequence of merging their reservation government with that of the Assiniboine. Economic conditions at Fort Belknap languished until the mid-1960's, when many Atsina were able to take advantage of federal War on Poverty programs. By 1980, Fort Belknap had the highest percentage of college graduates of any reservation of the northern Plains.
Sources: "Atsina." American Indians Ready Reference. Ed. Harvey Markowitz. Salem Press, Inc., 1995. eNotes.com. 13 Mar, 2014