 Others, such as Aleksandar Stipčević, argue that the process of romanization was rather selective and involved mostly urban centers but not the countryside, where previous Illyrian socio-political structures were adapted to Roman administration and political structure only in some necessities.Stanko Guldescu argued that the Vlachs, or Morlachs, were Latin speaking and pastoral peoples who lived in the Balkan mountains since pre-Roman times, and they are mentioned in the oldest Croatian chronicles

After the Western Roman Empire collapsed in 476, with the beginning of the Migration Period, Julius Nepos shortly ruled his diminished domain from the Diocletian palace after his 476 flight from Italy.The region was then ruled by the Ostrogoths up to 535, when Justinian I added the territory to the Byzantine Empire.