[jimmywanger]

Because up until very recently, very few people outside of China that were not ethnic Han spoke Chinese.

The concept of "Chinese" is fairly inaccurate anyways. I'd like to flatter myself that my mandarin is ok (I won't starve and I generally can make myself understood) but I can't understand most Cantonese. Cantonese is classified as a dialect of Mandarin, but it's really not mutually intelligible.