​ASSINIBOIN (“Stone-Cookers”), a tribe of North American Indians of Siouan stock. Their name (see above) is said to refer to their method of boiling water by dropping red-hot stones into it. Their former range was between the Missouri and the middle Saskatchewan on both sides of the Canadian frontier. In 1904 there were 1234 in the United States, all on reservations in Montana; and in 1902 there were 1371 in Canada.