and in 251 the Emperor Decius was killed in battle against them near Odessus on the Black Sea (the modern Varna).  The Goths reached the outskirts of Thessalonica (Salonika), but were defeated by the Emperor Claudius at Naissus (Nish) in 269; shortly afterwards, however, the Emperor Aurelian had definitively to relinquish Dacia to them.  The Emperor Diocletian, a native of Dalmatia, who reigned from 284 to 305, carried out a redistribution of the imperial provinces.  Pannonia and western Illyria, or Dalmatia, were assigned to the prefecture of Italy, Thrace to that of the Orient, while the whole centre of the peninsula, from the Danube to the Peloponnese, constituted the prefecture of Illyria, with Thessalonica as capital.  The territory to the north of the Danube having been lost, what is now western Bulgaria was renamed Dacia, while Moesia, the modern kingdom of Serbia, was made very much smaller.  Praevalis, or the southern part of Dalmatia, approximately the modern Montenegro and Albania, was detached from that province and added to the prefecture of Illyria.  In this way the boundary between the province of Dalmatia and the Balkan peninsula proper ran from near the lake of Scutari in the south to the river Drinus (the modern Drina), whose course it followed till the Save was reached in the north.

An event of far-reaching importance in the following century was the elevation by Constantine the Great of the Greek colony of Byzantium into the imperial city of Constantinople in 325.  This century also witnessed the arrival of the Huns in Europe from Asia.  They overwhelmed the Ostrogoths, between the Dnieper and the Dniester, in 375, and the Visigoths, settled in Transylvania and the modern Rumania, moved southwards in sympathy with this event.  The Emperor Valens lost his life fighting against these Goths in 378 at the great battle of Adrianople (a city established in Thrace by the Emperor Hadrian in the second century).  His successor, the Emperor Theodosius, placated them with gifts and made them guardians of the northern frontier, but at his death, in 395, they overran and devastated the entire peninsula, after which they proceeded to Italy.  After the death of the Emperor Theodosius the empire was divided, never to be joined into one whole again.  The dividing line followed that, already mentioned, which separated the prefecture of Italy from those of Illyria and the Orient, that is to say, it began in the south, on the shore of the Adriatic near the Bocche di Cattaro, and went due north along the valley of the Drina till the confluence of that river with the Save.  It will be seen that this division had consequences which have lasted to the present day.  Generally speaking, the Western Empire was Latin in language and character, while the Eastern was Greek, though owing to the importance of the Danubian provinces to Rome from the military point of view, and the lively intercourse maintained between them, Latin influence in them was for a long time stronger than Greek.  Its extent is proved by the fact that the people of modern Rumania are partly, and their language very largely, defended from those of the legions and colonies of the Emperor Trajan.