Building new worlds – new reflections of reality – is one of the most interesting parts of being a fantasy author. A fantasy setting has to be both new and familiar. It's the similarities that help to ground the story; it's the differences that make it interesting. Too much of one or the other, and you get a book that isn't fantasy at all, or a book that might as well be written in an alien language. As you might expect, different writers have different ideas about where the optimum balance lies!