The Great Wall: China Against the World, 1000 BC - AD 2000

Very well done book, covering how historical China's border-wall building was fueled by (and recursively lead to), their imperialist ambitions and isolationist attitudes, and how that would effect the country in the future. That said, some of the other elements that effect these attitudes (the unpredictability of the Yangtze river requiring any centralized government to focus it's attention inward on that in order to make sure everyone gets fed, is only given brief mention, which is kind of unfortunate.

Still, it's a good book, and you should check it out.