One of the book’s main themes is the seafaring tradition of China. The author gives copious information about this throughout different stages of China’s history. This may come as a surprise to some, as China is often thought of as a land-based and agricultural nation. Part of the book’s purpose is to highlight this tradition, which declined precipitously following the age of the treasure ships. Levathes’ point is that the more recent status was the exception, not the rule. For centuries before the Ming dynasty, China was active in the Pacific and Indian Oceans.

The main source of this tradition comes from the Yi peoples in China’s eastern and southern coastal regions. Cut off by mountains from the fertile lands inland, they turned to the sea rather than agriculture for sustenance, and their nautical knowledge spread to many other countries. They “are believed to be the world’s first ‘boat people,’ that is, the first people to cross a body of water and settle a new land”—first doing so during the last Ice Age 50,000 years ago (23). Some scholars believe that the Yi were the ancestors of Indonesians and Polynesians, both of whom have strong seafaring traditions.