I don't think that is totally true, Latvian Hound. I mean it is true that your average American dosen't know where New Zealand is for example, but does your average Chinese or Latvian? And if they do most likely they think New Zealand is either part of Australia or identical to it. I suspect it has something to do with being at the ends of the Earth, in a similar vein I couldn't tell you much about Siberia.
But from the producers point of view they have to make money, and they aren't going to make much if their potential customer walks up inspects the box and discovers that it features 24 civs that they have never heard of and 3 they vaguely remember but can't place. In the opposite of course, many Korean buyers might be more likely to buy the game if they noticed that it featured Korea. So at least some of the slots have to go to the countries the bought the most copies of Civ III and its expansions. So after they have the well known and well liked ones down (Rome, Egypt, Persia, etcetera) they put in the countries the buy the most copies (America, Korea, Germany, etcetera) notice there is quite a bit of overlap, China is not only well known but presumably buys quite a few copies as could be true of Russia, England, and so on.