The theme of 'Dragonwings' is change. People are usually worried about change, but the change most likely will have a positibe outcome, which is what happens with Moon Shadow and his family. The setting in the book first took place in China, which was Moon Shadow's first home.
Since you're already separating the city and country with commas, you use semicolons to separate the pairs to make it less confusing and easy to understand.
