Assiniboins, a tribe of Indians of the Dakota family, in Montana territory, United States, and in Manitoba and the region round about in British America. They were a part of the Yankton Sioux, but after a bitter quarrel about women separated from the mass of the nation about the beginning of the 17th century, and the two parties have since been hostile. Their own distinctive name is never used: the neighboring Algonquin tribes called them Assinipwalak, Stone Sioux, or Stone Warriors, as some infer from the nature of their country near the Lake of the Woods, The adventurous French missionaries reported them as a nation as early as 1640, and at a very early period they traded furs on Hudson bay. In the British provinces they are divided into Assiniboins of the prairies, who are tall, vigorous, and thievish, and Assiniboins of the woods, who are wretchedly poor. They extend from Souris or Mouse river to the Athabasca, and number some 5,000. There are Roman Catholic and Methodist missions among them at Lake Ste. Anne and Pigeon lake. They are friends and allies of the Crees, and live intermixed with them.

In the United States the Red Stone Assiniboins and Upper As-siniboins were estimated in 1871 at 4,850 souls.