The completion of the Indian frontier to the upper lakes was the work of the early thirties. The purchase at Fort Armstrong had made the line follow the north boundary of Missouri and run along the west line of this Black Hawk purchase to the Neutral Strip. A second Black Hawk purchase in 1837 reduced their lands by a million and a quarter acres just west of the purchase of 1832. Other agreements with the Potawatomi, the Sioux, the Menominee, and the Chippewa established a final line. Of these four nations, one was removed and the others forced back within their former territories. The Potawatomi, more correctly known as the Chippewa, Ottawa, and Potawatomi, since the tribe consisted of Indians related by marriage but representing these three stocks, had occupied the west shore of Lake Michigan from Chicago to Milwaukee. After a great council at Chicago in 1833 they agreed to cross the Mississippi and take up lands west of the Sauk and Foxes and east of the Missouri, in present Iowa. The Menominee, their neighbors to the north, with a shore line from Milwaukee to the Menominee River, gave up their lake front during these years, agreeing in 1836 to live on diminished lands west of Green Bay and including the left bank of the Wisconsin River. The Sioux and Chippewa receded to the north. Always hereditary enemies, they had accepted a common but ineffectual demarcation line at the old treaty of Prairie du Chien in 1825. In 1837 both tribes made further cessions, introducing between themselves the greater portion of Wisconsin. The Sioux acknowledged the Mississippi as their future eastern boundary, while the Chippewa accepted a new line which left the Mississippi at its junction with the Crow Wing, ran north of Lake St. Croix, and extended thence to the north side of the Menominee country. With trifling exceptions, the north flank of the Indian frontier had been completed by 1837. It lay beyond the farthest line of white occupation, and extended unbroken from the bend of the Missouri to Green Bay. While the north flank of the Indian frontier was being established beyond the probable limits of white advance, its south flank was extended in an unbroken series of reservations from the bend of the Missouri to the Texas line. The old Spanish boundary of the Sabine River and the hundredth meridian remained in 1840 the western limit of the United States. Farther west the Comanche and the plains Indians roamed indiscriminately over Texas and the United States. The Caddo, in 1835, were persuaded to leave Louisiana and cross the Sabine into Texas; while the quieting of the Osage title in 1825 had freed the country north of the Red River from native occupants and opened the way for the colonizing policy.