Following the split of the Empire between 337 and 395 AD, Dalmatia and Pannonia became parts of the Western Roman Empire. The region was conquered by the Ostrogoths in 455 AD. It subsequently changed hands between the Alans and the Huns. By the 6th century, Emperor Justinian I had reconquered the area for the Byzantine Empire. Slavs overwhelmed the Balkans in the 6th and 7th centuries. Illyrian cultural traits were adopted by the South Slavs, as evidenced in certain customs and traditions, placenames, etc.