The seeds of the Papal States as a sovereign political entity were planted in the 6th century. Beginning in 535, the Eastern Roman Empire—referred to by most historians as the Byzantine Empire to distinguish the Greek-speaking and religiously Orthodox polity based in Constantinople from its Latin-speaking, Catholic predecessor ruled from Rome —under Emperor Justinian I, launched a reconquest of Italy that took decades and devastated Italy's political and economic structures. In 568 the Lombards entered the peninsula from the north, establishing an Italian kingdom, and over the next two centuries would conquer most of the Italian territory regained by Byzantium. By the 7th century, Byzantine authority was largely limited to a diagonal band running roughly from Ravenna, where the emperor's representative, or Exarch, was located, to Rome and south to Naples, plus coastal exclaves. North of Naples, the band of Byzantine control contracted and the borders of the "Rome-Ravenna corridor" were extremely narrow.