22 ABORIGINAL MONUMENTS
fact, it is that the pressure of hostilities was from the north- east; or that, if the tide of migration flowed from the south, it received its final check upon this line. On the other hypothesis, that in this region originated a semi-civilization which subsequently went southward, constantly developing itself in its progress, until it attained its height in Mexico, we may suppose from this direction came the hostile savage hoards, before whose incessant attacks the less warlike mound-builders gradually receded, or beneath whose exter- minating cruelty they entirely disappeared—leaving these monuments alone to attest their existence, and the extraor- dinary skill with which they defended their altars and their homes. Upon either assumption it is clear that the con- test was a protracted one, and that the race of the mounds were for a long period constantly exposed to attack. This conclusion finds its support in the fact that, in the vicinity of those localities, where, from the amount of remains, it appears the ancient population was most dense, we almost invariably find one or more works of a defensive character, furnishing ready places of resort in times of danger. We may suppose that a state of things existed somewhat analogous to that which attended the advance of our pioneer population, when every settlement had its little fort, to which the settlers flocked in case of alarm or attack.
It may be suggested that there existed among the mound-builders a state of society something like that which prevailed amongst the Indians; that each tribe had its separate seat, maintaining an almost constant warfare against its neighbors, and, as a consequence, possessing its own “castle,” as a place of final resort when invaded by a powerful foe. Apart from the fact, however, that the In- dians were hunters, averse to labor, and not known to have constructed any works approaching, in skilfulness of design or in magnitude, those under notice, there is almost posi- tive evidence that the mound-builders were an agricul-
