I use soundtracks of movies which theme is quite the same of the nation I'm playing - for Ulm i.e. Conan the Barbarian (very good ost imho), mictlan=apocalypto, ea ermor=the gladiator, t'ien c'hi= House of Flying Daggers, Hero, Crouching Tiger Hidden Dragon... for the ones without a specific movie's ost, I just go for general "epic movies".
