The necessary precondition for a world art history is the close study of cultural exchanges. Even nowadays, when you can travel from New York to Beijing in less than a day, the distance between America’s and China’s visual cultures is still immense. When such travel was much slower, and curators were not much concerned with exotic art, the diverse artistic traditions were relatively self-sufficient. But once Vasco da Gama circumnavigated the globe, it was inevitable...