In the world of the late twentieth century, events on one continent 1ROUTINE influence developments on the others, for good or for ill. In the broad expanse of 2HISTORY time, however, these 3EXTEND connections developed quite recently, starting in the fifteenth and sixteenth centuries. In one sense, the process began with Christopher Columbus’s four voyages, the first 4ATLANTIC excursions to have far-reaching and long-lasting consequences. In another sense, however, Columbus’s voyages were less a beginning than the 5CONTINUE of a centuries-old human process of 6EXPLORE and migration. When Columbus was born, Europe, Africa, and Asia were each part of the Old World of the Eastern Hemisphere, but they were also separate worlds culturally, 7RELIGION and politically. Columbus’s voyages shattered that 8ISOLATE once and for all, in what is arguably the most fateful encounter between disparate human groups that history has ever known.