Aside from the general instruction of something pan-Western/African/Orchestral, there was little guidance as to the actual song. Soren, being a good musician himself, had one note for me as I was writing it. He said "I think you should write a bridge". That was a great note, as the 'Ufalme walko' section was written after that note.
I also wrote the music for the opening movie... where you're zooming in from outer space, into the coronation scene. But that was it.
One thing I forgot to mention that I thought you might like to hear: Civ IV was my introduction to the game Civilization. I bought the original on a whim. Warlords and Beyond the Sword I bought very soon after they were released.
Why do I mention this? Here's why: I was so disappointed with the intro movie and music to Warlords that I actually made the effort to change them back to the originals with your music. I found it funny that BTS was actually released with that as a built-in option. That Firaxis would go through the trouble to add that feature for the game fans I think is a huge compliment to you!
(Granted, the original intro movie was also the most inspired of the three!)