was derived from the Ojibway term , stone, and the French , to boil, but such an etymology is very unlikely. Language Assiniboine is a Mississippi Valley Siouan language, in the Western Siouan language family. In the early 21st century, about 150 people speak the language and most are more than 40 years old. The majority of the Assiniboine today speak only American English. The 2000 census showed 3,946 tribal members who lived in the United States. Assiniboine are closely linked by language to the Stoney First Nations people of Alberta. The latter two tribes speak varieties of Nakota, a distant, but not mutually intelligible, variant of the Sioux language. History Early history The Assiniboine, along with the Stoney of Alberta, share a common ancestry with the Sioux nation. While it was formerly believed that the Assiniboine originated among the Yanktonai division of the Dakota Sioux, linguistic analysis indicates that the Assiniboine and Stoney together form a group coordinate with that of the Santee, Lakota, and Yankon-Yanktonai, and that they are no more related to one of these subdivisions than another. The separation of the Assiniboine from the Sioux must have occurred at some time prior to 1640, as Paul Le Jeune names them along with the "Naduessi" (Sioux) in his Jesuit Relations of that year. The Assiniboine and Sioux were both gradually pushed westward onto the plains from the woodlands of Minnesota by the Ojibwe, who had acquired firearms from their French allies. Later, the Assiniboine acquired horses via raiding and trading with neighboring tribes of Plains Indians such as the Crow and the Sioux on their south. The Assiniboine eventually developed into a large and powerful people with a horse and warrior culture; they used the horse to hunt the vast numbers of bison that lived within and outside their territory. At the height of their power, the Assiniboine dominated territory ranging from the North Saskatchewan River in the north to the Missouri River in the south, and including portions of modern-day Saskatchewan, Alberta, and Manitoba, Canada; and North Dakota and Montana, United States of America. Contact with Europeans and fur trade The first person of European descent to describe the Assiniboine was an employee of the Hudson's Bay Company named Henry Kelsey in the 1690s. Later explorers and traders Jean Baptiste de La Vérendrye and his sons (1730s), Anthony Henday (1754–55), and Alexander Henry the younger (1800s)