Assiniboine Indians, a tribe of the Siouan linguistic group, closely related to the Yanktonai Sioux. The Assiniboine were a hunting people who lived along the Saskatchewan and Assiniboine rivers in Canada, and north of the Milk and Missouri rivers in Montana. They were a large tribe, numbering about 10,000 in the 17th century. In 1836 smallpox killed some 4,000. The tribe was assigned to reservations in the late 19th century. There are approximately 3,500 Assiniboine living on reservations in Montana. Over 3,500 of the tribe live on reservations in Alberta and Saskatchewan.