In 1421, the largest fleet the world had ever seen sailed from its base in China. The ships, huge junks nearly 500 feet long and built from the finest teak, were under the command of Emperor Zhu Di’s loyal eunuch admirals. Their mission was to proceed all the way to the end of the earth to collect tribute from the barbarians beyond the seas and unite the whole world in Confucian harmony. Their journey would last over two years and circle the globe. When they returned, Zhu Di had lost power and China was beginning its long, self-imposed isolation from the world. The great ships rotted and the records of their journeys were destroyed. Lost was the knowledge that Chinese ships had reached America 70 years before Columbus and circumnavigated the globe a century before Magellan. They had also discovered Antarctica, reached Australia 350 years before Cook, and solved the problem of longitude 300 years before the Europeans.