As a result of my examination and discussion of the burial mounds of Wisconsin, I reached the conclusion that they were built by the Indian tribes found inhabiting that section at the advent of the whites, or by their ancestors. The data, of which but a comparatively small portion is given, seem to justify this conclusion. But the case is somewhat different in reference to the works of the Ohio district. Although the data obtained here point with satisfactory certainty to the conclusion that Indians were the authors of these works, it cannot be claimed that all or even the larger portion of them were built by Indians inhabiting the district when first visited by the whites, or by their ancestors. [Illustration: PL. VI. ENLARGED PLAN OF PART OF THE WORKS SHOWN IN PL. V.] Hence the mystery which enshrouds them is deeper and much more difficult to penetrate than that which hangs about the antiquities of some of the other districts; in fact, they present probably the most difficult problem for solution in this respect of any ancient works of our country. That some of the burial mounds, graves, and other works are to be attributed to Indians who entered this district after the Europeans had planted colonies in Canada and along the Atlantic coast is probably true, but that much the greater portion of the typical works belong to a more distant period must be conceded. It is a singular fact that in the latter half of the seventeenth century, when European explorers began to penetrate into this region, what is now the State of Ohio was uninhabited. The Miami confederacy, inhabiting the southern shore of Lake Michigan, extended southeasterly to the Wabash. The Illinois confederacy extended down the eastern shore of the Mississippi to about where Memphis now stands. The Cherokees occupied the slopes and valleys of the mountains about the borders of what is now East Tennessee, North Carolina, and Georgia. The great basin bounded north by Lake Erie, the Miamis, and the Illinois, west by the Mississippi, east by the Alleghanies, and south by the headwaters of the streams that flow into the Gulf of Mexico, seems to have been uninhabited except by bands of Shawnees, and scarcely visited except by war parties of the Five Nations.[35]