It grossly corresponds to the upper valley of the Melfa river, which runs through it before joining the Liri.

In Livy's History of Rome, there are early references to Cominium as the site of a battle between the Samnites and the Romans.

Some suggest that the town of San Donato is the ancient Cominium, others believe the battle site was at Vicalvi.

For a period it was also contested between the monasteries of Monte Cassino and San Vincenzo al Volturno.

In the past, the valley was characterized by a strong presence of land sown with wheat, maize and lucerne and cultivations of vines and olive trees.