This ancient race seems to have occupied nearly the whole basin of the Mississippi and its tributaries, with the fertile plains along the Gulf, and their settlements were continued across the Rio Grande into Mexico; but toward their eastern, northern, and western limit the population was evidently smaller, and their occupation of the territory less complete than in the Valley of the Ohio, and from that point down to the Gulf. No other united people previous to our time can be supposed to have occupied so large an extent of territory in this part of North America.
It has heretofore been stated that remains of this people exist in Western New York, but a more intelligent and careful examination shows that the works in Western New York are not remains of the Mound-Builders. This is now the opinion of Mr. Squier, formed on personal investigation since the great work of Squier and Davis was published.
It is usual to rank the civilized life of the Mound-Builders much below that of the ancient people of Mexico and Central America. This may be correct, for the remains as they now exist appear to justify it. But if all the ancient stone-work in Central America, with its finely-carved inscriptions and wonderful decorations, had disappeared in the ages before Europeans visited this continent, the difference might not appear to be so great; for then the Central American remains, consisting only of earth-works, truncated pyramids, pyramidal foundations, and their connected works made of earth, would have a closer resemblance to works of the Mound-Builders, to those especially found on the lower Mississippi. On the other hand, if we now had in the Ohio and Mississippi Valleys remains of the more important edifices anciently constructed there, the Mound-Builders might be placed considerably higher in the scale of civilization than it has been customary to allow.
It can be seen, without long study of their works as we know them, that the Mound-Builders had a certain degree of civilization which raised them far above the condition of savages. To make such works possible under any circumstances, there must be settled life, with its accumulations and intelligently organized industry. Fixed habits of useful work, directed by intelligence, are what barbarous tribes lack most of all. A profound change in this respect is indispensable to the beginning of civilization in such tribes.