Gaul faction uncovered in Total War: Rome II

These people have a "complex and sophisticated culture" in their stronghold of Nemossos. Kings and tribal chieftains, taking counsel from Druids, are the leading force in the Arverni.

The hordes from Gaul have plagued Rome and even sacked it in 390BC. Put simply they're a right pain in the rear of any 'civilized' faction looking to expand borders.

"Ruled by kings and tribal chieftains, but deferent to their druids, there exists a rigid social order amongst the Arverni. Prestige and power come from a man's abilities as a warrior and a leader as much as his lineage," reads the Arveni faction wikia page. Creative Assembly have put together an official wikia for all of Total War.

"Heavily dependent on infantry, the Arverni make great use of javelins and the devastating impact of the charge, led by elite warriors such as Spear Nobles and Oathsworn. It is by fighting this way that leaders have earned their places: as champions, proving themselves in conflict."

"While many matters ostensibly fall to the Arverni's kings and chieftains, in reality, much is governed by the will of the druids, including declarations of war or peace. Blending animism with a pantheon of greater, local and lesser household gods, the Celtic religion is one of the key factors uniting the disparate Gallic tribes."

The other barbarian faction revealed so far is the Iceni, at home in Southern Britain.

Total War: Rome II releases on PC in October 2013.