Prior to these secessions another affiliated tribe, the Miamis, had broken off from the Ojibwa stock, or the common parent tribe, and migrated to central Illinois and western Indiana. Following in the track of this migration were the Illinois, another and later offshoot from the same stem, who afterwards subdivided into the Peorias, Kaskaskias, Weaws, and Piankeshaws. Their dialects, with that of the Miamis, find their nearest affinity with the Ojibwa, and next with the Cree.[78] The outflow of all these tribes from the central seat at the great fisheries of Lake Superior is a significant fact, because it illustrates the manner in which tribes are formed in connection with natural centres of subsistence. The New England, Delaware, Maryland, Virginia and Carolina Algonkins were, in all probability, derived from the same source. Several centuries would be required for the formation of the dialects first named, and for the production of the amount of variation they now exhibit.
The foregoing examples represent the natural process by which tribes are evolved from each other, or from a parent tribe established in an advantageous position. Each emigrating band was in the nature of a military colony, if it may be so strongly characterized, seeking to acquire and hold a new area; preserving at first, and as long as possible, a connection with the mother tribe. By these successive movements they sought to expand their joint possessions, and afterward to resist the intrusion of alien people within their limits. It is a noticeable fact that Indian tribes speaking dialects of the same stock language have usually been found in territorial continuity, however extended their common area. The same has, in the main, been true of all the tribes of mankind linguistically united. It is because the people, spreading from some geographical centre, and maintaining an arduous struggle for subsistence, and for the possession of their new territories, have preserved their connection with the mother land as a means of succor in times of danger, and as a place of refuge in calamity.
It required special advantages in the means of subsistence to render any area an initial point of migration through the gradual development of a surplus population. These natural centres were few in number in North America. There are but three. First among them is the Valley of the Columbia, the most extraordinary region on the face of the earth in the variety and amount of subsistence it afforded, prior to the cultivation of maize and plants;[79] second, the peninsula between Lakes Superior, Huron and Michigan, the seat of the Ojibwas, and the nursery land of many Indian tribes; and third, the lake region in Minnesota, the nursery ground of the present Dakota tribes. These are the only regions in North America that can be called natural centres of subsistence, and natural sources of surplus numbers. There are reasons for believing that Minnesota was a part of the Algonkin area before it was occupied by the Dakotas. When the cultivation of maize and plants came in, it tended to localize the people and support them in smaller areas, as well as to increase their numbers; but it failed to transfer the control of the continent to the most advanced tribes of Village Indians, who subsisted almost entirely by cultivation. Horticulture spread among the principal tribes in the Lower Status of barbarism and greatly improved their condition. They held, with the non-horticultural tribes, the great areas of North America when it was discovered, and from their ranks the continent was being replenished with inhabitants.[80]