[abjwam]

Don't think that's true. I'm in southeast asia and the largest chinese language groups in the following countries are:

Singapore: Hokkien

Indonesia: Teochew

Philippines: Hokkien

Malaysia: Hokkien (although cantonese popular there)

Thailand: Teochew

Teochew and Hokkien are actually part of the min-nan dialect group which also includes Taiwanese.

[smallnamespace]

That's fair, but anything outside of SE Asia is predominantly Cantonese, hence why Westerners are familiar with it.

There's also the fact that the HK film industry was fairly dominant for a couple of decades--if a Westerner saw a Chinese-language film before the 90s, it almost certainly had Cantonese in it.