How was it calculated? I just won an Marathon game on Emperor, dominance around 1000AD, and I only got a score of 11760. Usually when I win on dominance it's around 40k. Not that matters but why is that? Is it because I was playing from a saved map from scenario?

1) How big was the map?
2) How many opponents?
3) your population at the time of the victory matters.

If you mouse over your score at any point in the game it will tell you what your score would be if you finished the game on that turn. You would'nt have any surprises if you do that.