We do know that the first wagon journey that led to to today's America was at least four thousand years ago. They brought the wheel to Egypt. Before them, the Egyptians had no wheel. Egypt had no iron until another group of people rolled south, an Indo-European group called the Hittites, and brought it with them. Egyptian history is filled with these northern invasions.
Greek history is also a series of northern invasions.
Then Roman history becomes a series of northern invasions. In fact, the Italic tribes, some of whom became Romans themselves, were almost certainly northern invaders into the Italian peninsula before history takes note of them. But the people who rolled into Egypt and into Greece and into Rome were not only from the north, but from the west as well. Aryan is also the word those who invaded India from the north and set up the caste system called themselves. Other branches of this same westward drive ended up in America and bred you and me.