First, you right-click on start. Then you click explore and then program files on the left side of the screen. Then you find activision and click on that and should the Rome: Total War folder. Open it. Then in this order you open data, world, maps, campain, imperial campaign, and finally descr-strat. Now, you should see a list of all the factions in the game. Here, you move the factions listed under end unlockable and end unplayable to campaign playable. Congratulations, you've just unlocked some new factions! However, be careful not to unlock more than one or two at a time as this can cause problems in your game. I hope this helps.