After the fall of the in 774, the duchy became the sole Lombard territory which continued to exist as a rump state, maintaining its de facto independence for nearly 300 years as the Principality of Benevento.

According to some scholars, Lombards were present in southern Italy well before the complete conquest of the Po Valley: the duchy by these accounts would have been founded in 571.

After his reign, Byzantine holdings in southern Italy were reduced to Naples, Amalfi, Gaeta, Sorrento, Calabria, and the maritime cities of Apulia (Bari, Brindisi, Otranto, etc.).

In 663, the city itself was besieged by the Byzantines during the failed attempt of Constans II, who had disembarked at Taranto, to recover southern Italy.

In the following decades, Benevento conquered some territories from the Byzantines, but the main enemy of the duchy was now the northern Lombard kingdom itself.

His successor, Ratchis, declared the duchies of Spoleto and Benevento foreign countries where it was forbidden to travel without royal permission.