I was looking at the music file and I think you can just copy and paste and then specify Egypt etc to use it.

I think the game searches the header and activates with a pacticular faction is mentioned.

So instead of have all the eastern egypt carthage etc all LUMPED together you can have each one having unique music. I havent tried this, but maybe some one would give it a shot.

Just dont forget to delete the events.dat file first. lol