 Because of his restoration activities , Justinian has sometimes been called the " last Roman " in modern historiography . This ambition was expressed by the partial recovery of the territories of the defunct western Roman empire . His general , Belisarius , swiftly conquered the Vandal kingdom in North Africa . Subsequently Belisarius , Narses , and other generals conquered the Ostrogothic kingdom , restoring Dalmatia , Sicily , Italy , and Rome to the empire after more than half a century of rule by the Ostrogoths . The prefect Liberius reclaimed the south of the Iberian peninsula , establishing the province of Spania . These campaigns re @-@ established Roman control over the western Mediterranean , increasing the Empire 's annual revenue by over a million solidi . During his reign Justinian also subdued the Tzani , a people on the east coast of the Black Sea that had never been under Roman rule before . 
