Although an invasion attempt by the Franks, then allies of the Ostrogoths, late in the war was successfully repelled, a large migration by the Lombards, a Germanic people that had been previously allied with the Byzantine Empire, ensued. In the spring of 568 the Lombards, led by King Alboin, moved from Pannonia and quickly overwhelmed the small Byzantine army left by Narses to guard Italy.

The Lombard arrival broke the political unity of the Italian Peninsula for the first time since the Roman conquest (between the 3rd and 2nd century BCE). The peninsula was now torn between territories ruled by the Lombards and the Byzantines, with boundaries that changed over time.

The newly arrived Lombards were divided into two main areas in Italy: the Langobardia Maior, which comprised northern Italy gravitating around the capital of the Lombard kingdom, Ticinum (the modern-day city of Pavia in the Italian region of Lombardy); and Langobardia Minor, which included the Lombard duchies of Spoleto and Benevento in southern Italy. The territories which remained under Byzantine control were called "Romania" (today's Italian region of Romagna) in northeastern Italy and had its stronghold in the Exarchate of Ravenna.