just in case you wanted to know,

Tear Rome apart by leading hordes of barbarians or stand and defend the Empire as a leader of one of the two former Romes, the Western and Eastern Empires. 200 years have now passed since the main campaign in Rome: Total War. The expansion offers RTS gamers 10 new factions and new gameplay features such as night battles, combat effects, and fighting styles. Players can now control vast armies and over 100 new units as they battle across an updated European map that now reflects the historical changes since Rome: Total War.

"Fans of Total War and RTS games can now defend or sack the Roman Empire with an unparalleled level of historical accuracy and gameplay options," said Scott A. Steinberg, Vice President of Marketing, SEGA of America, Inc. "SEGA is committed to maintaining the vitality of the Total War brand and will continue to support fans with great expansions and leading edge RTS content."

Rome: Total War - Barbarian Invasion commences just after the last Emperor of a unified Rome has died. His successors in Rome and Constantinople are now uneasy allies and rivals for power. The barbarians' are massing along the borders, and in some cases are living inside what used to be Roman territory.

Key features

Newly designed campaign map; this reflects 200 years of change and turmoil to conquer new lands and new region boundaries.
10 new playable factions; expanded barbarian tech tree, 85 new units, 21 new buildings, ancillary characters, vices and virtues, military commands, holy relics and much more!
Updated gameplay featuring the Hordes, Character Loyalty, and Roman Civil wars. Barbarians can also relocate to a new land after losing their last settlement, otherwise known as the "Barbarian Migration."
Night battles ^Ö Hugely atmospheric battles and combat effects with added tactical challenges.
Improved battle AI and tactics - Individual faction fighting styles, swimming units across rivers and various new tactics.