 After the fall of Rome, the key challenge to the Byzantine Empire was to maintain a set of relations between itself and its sundry neighbors, including the Persians, Georgians, Iberians, the Germanic peoples, the Bulgars, the Slavs, the Armenians, the Huns, the Avars, the Franks, the Lombards, and the Arabs, that embodied and so maintained its imperial status.All these neighbors lacked a key resource that Byzantium had taken over from Rome, namely a formalized legal structure.When they set about forging formal political institutions, they were dependent on the empire.