The Romans have come seeking new lands, and have completely taken over the Swadians. And the Gauls, having lost all their lands to the Romans, came and took over the Nords. Now the Rhodoks, Veagirs, Khergits and Sarranids realize that the Romans and Gauls pose a threat to their kingdoms. You arrive in Caladria, with a huge war goes on.
This Mod is execptional however, more work could have gone into converting the other vanilla factions into Roman Invasion (Sarranids being Carthage, Greeks being thrown in, that sort of the stuff) I also did not find much new content when it came to NPC's