For thousands of years, the legend of a great flood has endured in the biblical story of Noah and in such Middle Eastern myths as the epic of Gilgamesh. Few believed that such a catastrophic deluge had actually occurred. But now geophysicists have discovered an event that changed history, a sensational flood 7,600 years ago in what is today the Black Sea. Using sound waves and coring devices to probe the sea floor, they discovered clear evidence that this inland body of water had once been a vast freshwater lake lying hundreds of feet below the level of the world's rising oceans. The authors explore the archaeological, genetic, and linguistic evidence suggesting that the flood rapidly created a human diaspora that spread as far as Western Europe, Central Asia, China, Egypt, and the Persian Gulf. They suggest that the Black Sea People could well have been the mysterious proto-Sumerians, who developed the first great civilization in Mesopotamia, the source of our own.