This is all the music in MP3 format from the (game)\assets\sounds directory of Sid Meier's Civilization IV.
I've set the status to "official" on this release because the music comes with the game and it doesn't take any "hackery" to access it. Anyone who owns the game can simply copy the "Soundtrack" and "Diplomacy" folders from the game to their music collection.
The medium names are the names of the folders containing the music files.
The original files have no metadata beyond the file names. Some of these are very generic (AncientSoundtrack1.mp3), while others give at least some information (BachBrandenburg2 3.mp3).
Most of the information on composers and works comes from Wikipedia.
Where I could match the files with songs on the official soundtrack CD, I've used those artist credits.
