Gregory Cochran asks an alternative history favorite question: what period of Old World history did the New World civilizations correspond to at time of contact? Cochran's answer: about 2,400 BCE. In his estimation, Europeans were effectively invaders from the far future.
Above: the pyramid of Cheops, ca. 2560 BCE. Below: the great pyramid at Teotihuacan just outside Mexico City, built ca. 200 CE.