Wikipedia
The Hernici were an Italic tribe of ancient Italy, whose territory was in Latium between the Fucine Lake and the Sacco River (Trerus), bounded by the Volsci on the south, and by the Aequi and the Marsi on the north.
In 495 BC Livy records that they entered into a treaty with the Volsci against ancient Rome.
They long maintained their independence, and in 486 BC were still strong enough to conclude an equal treaty with the Latins. They broke away from Rome in 362 and in 306, when their chief town Anagnia was taken and reduced to a praefectura, but Ferentinum, Aletrium and Verulae were rewarded for their fidelity by being allowed to remain free municipia, a position which at that date they preferred to the civitas.
The name of the Hernici, like that of the Volsci, is missing from the list of Italian peoples whom Polybius describes as able to furnish troops in 225 BC; by that date, therefore, their territory cannot have been distinguished from Latium generally, and it seems probable that they had then received the full Roman citizenship. The oldest Latin inscriptions of the district (from Ferentinum) are earlier than the Social War, and present no local characteristic.