The hollow beating of his footstep seems A sacrilegious sound. I think of those Upon whose rest he tramples. Are they here— The dead of other days?—and did the dust Of these fair solitudes once stir with life And burn with passion? Let the mighty mounds That overlook the rivers, or that rise In the dim forest crowded with old oaks, Answer. A race, that long has passed away, Built them;—a disciplined and populous race Heaped, with long toil, the earth, while yet the Greek Was hewing the Pentelicus to forms Of symmetry, and rearing on its rock The glittering Parthenon. These ample fields Nourished their harvests, here their herds were fed, When haply by their stalls the bison lowed, And bowed his maned shoulder to the yoke. All day this desert murmured with their toils, Till twilight blushed, and lovers walked, and wooed In a forgotten language, and old tunes, From instruments of unremembered form, Gave the soft winds a voice. The red man came— The roaming hunter tribes, warlike and fierce, And the mound-builders vanished from the earth. The solitude of centuries untold Has settled where they dwelt.
This section of the poem clearly mentions the mound-builders. It is evident that Bryant sees these people as a superior people and compares the people and their ruins to that of Greeks, and romanticizes this lost race with it's 'forgotten language and their past buried. Bryant says it was the 'red man' who is supposed to be the natives that were then in place of this lost civilization, who are the cause of the mound-builder civilization to vanish.