History is littered with cases in which countries were isolated, sometimes because they chose to cut themselves off to protect their cultures (e.g., the late Tang, late Ming, and early PRC periods in China, and the Edo period in Japan) and sometimes because of circumstances like natural disasters and internal fighting. Both reasons lead them to fall behind in their technology, with terrible consequences. In fact, it is one of the most common reasons for empires and dynasties failing.
