Now our understanding of this civilization is once again threatened with obscurity. The Sudanese government is building a hydroelectric dam along the Nile, 600 miles upstream from the Aswan High Dam, which Egypt constructed in the 1960s, consigning much of lower Nubia to the bottom of Lake Nasser (called Lake Nubia in Sudan). By 2009, the massive Merowe Dam should be complete, and a 106-mile-long lake will flood the terrain abutting the Nile’s Fourth Cataract, or rapid, including thousands of unexplored sites. For the past nine years, archaeologists have flocked to the region, furiously digging before another repository of Nubian history goes the way of Atlantis.