Natives of the Bay. The Chesapeake Bay was a very different place between 18,000 and 11,500 years ago, at the end of the last ice age. As the climate moderated and rivers found their modern-day courses, plants and animals became established, and the once-barren plain was replaced with swamps, lagoons, grasslands, and forests. These changes made the area habitable for humans. Archeologists generally agree that the first inhabitants of the Chesapeake region arrived between 12,000 and 11,500 years ago, while glaciers were retreating; some, however, suggest an arrival several thousand years earlier.