Cunning Linguist, you pointed out something very important in regards to the way chinese people treat each other. Indeed what can be labled as xenophobic behavior is all over this country. The habitually close minded mindset of not dealing with your neighbors and not assisting others because it's none of your business has created a unique, prejudiced behavior that closes off the locals' minds before they even begin to interact with people from a different area. It may even sound positive in many situations as you will hear chinese people say things like, "I know a person who is from village/city/province" but it cannot really be taken as a sign of them really seeing the person as a friend even if they say they are. It's different from when you hear people in the USA say it. You know it's someone whom they don't hold a prejudice against because of the geography. Saying the exact same kind of thing from two entirely different countries really does mean two entirely different things.

Neighboring countries in Asia have mostly heard of and maybe read the famous novel written back in the Ming Dynasty called "The Three Kingdoms" or in some cases in which it is knows as, "The Romance of the Three Kingdoms". While in china people treat the novel as entertainment and even as a compilation of unwritten rules in terms of socializing, others who are not from the country see the book as accurate indication of how chinese people treat each other, which the chinese don't actually realize in a sense. If you know the book you should know what I mean.