Expansion offers little for its price tag
It adds 4 new civilizations: France, Russia and two other civilizations which are part of a new region - the African Region.
It allows you to activate neutral tribes. These neutral tribes start around randomly on the map, claiming a territory to themselves. You can either trade with them, and recieve a bonus, or you can simply wipe them out.
It's sort of a fun concept in my opinion, but I suppose it can also be viewed as useless to others.
The expansion also provides a few basically irrelevant gameplay tweaks(such as Artillery being able to become heroes) and a new game mode.
The expansion also improves the game's graphics.
Overall, it's a great game, but unless you wait for the price to drop or you're loaded with cash- I don't suggest purchasing this expansion.