“In a pretty extreme overreaction to the continued operation of Japanese pirates, they resurrected the old policy of haijin—an almost complete ban on any maritime shipping. Distracted by ongoing battles with the Mongols in the north, foreign diplomatic missions were seen as an unnecessary expense, the money better spent on a different project: the construction of a very large border wall. In the following years, China turned increasingly inward, shutting out the world. The fact that they did this just at the point when European navies were starting to explore the globe had a double effect: it meant that when the Europeans started to show up in Asian waters a few decades later, there wasn’t a major local power to stand in their way, and it meant that China kind of missed out on much of the scientific and technological acceleration that was kicking off. It would be a long, long time before the country regained its status as a world power.”