In the decline of the Roman Empire in the 600s, the Vlachs, Latin speaking natives of the Balkans, inhabited Croatia. Over hundreds of years, the Slavs migrated southward from the area of today's Czech Republic, towards Kosovo. The Vlachs, who called themselves Aromanians, dealt with raids from these Slavs, but were not seriously threatened.

Kosovo was not part of the medieval Serbian Kingdom of Rascia. In fact, Serbs did not seriously move into the region until the 1100s. The region was a sort of Neutral Zone between Bulgarian and Rascian territory, along with sections of Macedonia.

From 1014-1018, Kosovo was controlled by the Bulgars. In 1018, Byzantine Emperor Basil "The Bulgar Killer" assaulted Bulgarian territory throughout the Balkans. The Vlachs, whom the modern Albanians are probably descended from, continued to live in Kosovo despite the warfare.

Kosovo not only sat on the Byzantine/Bulgar/Serb divide, it also sat on the Roman Catholic/Eastern Orthodox divide.