One way to sum up the new scholarship is to say that it has begun, at last, to fill in one of the biggest blanks in history: the Western Hemisphere before 1492. It was, in the current view, a thriving, stunningly diverse place, a tumult of languages, trade, and culture, a region where tens of millions of people loved and hated and worshipped as people do everywhere. Much of this world vanished after Columbus, swept away by disease and subjugation. So thorough was the erasure that within a few generations neither conqueror nor conquered knew that this world had existed.