Europeans arrive. Native cultures are threatened. It is estimated that in 1491, 78,000,000 people lived in North, South and Central America. By AD 1500, 5,000,000 indigenous people, decimated by disease and war, remain. As for the City of the Sun, the Illinois remnants are now one of the one hundred World Heritage Sites. William Clark, of the Lewis and Clark Expedition, the first American Indian agent for the western United States and territories, oversees the destruction of the Missouri mounds before the Civil War, to make room for the city of St. Louis: The Mound City.