In 2002, retired submarine commander Gavin Menzies presented a lecture in which he claimed a Chinese fleet under Admiral Zheng He began a series of voyages in 1421 that would ultimately discover the North American continent. Menzies’s theory threatened the previously held belief that Columbus was the first explorer to travel to North America in 1492. Menzies believed European explorers like Columbus had maps prior to their expeditions. He concluded that only China had the resources to create such maps, build sea worthy ships and undertake an exploration of that scope. In this video segment adapted from 1421: The Year the Chinese Discovered America? learn how Menzies came to these conclusions. For more about Chinese exploration, see “The Voyage of Zheng He - II.”