Although they extended eastwards along the chain of the Apennines to the frontiers of the Arretines and the territory of Mutina (modern Modena) and Bononia (modern Bologna), the upper valley of the Macra about Pontremoli, an area later known as Lunigiana, and the adjoining Upper Garfagnana were their center.
The first objective of the insurgents were the Roman colonies of Placentia and Cremona, causing the Romans to flee to Mutina (modern Modena), which the Gauls then besieged.