The Roman province of Illyricum replaced the formerly independent kingdom of Illyria. It stretched from the Drin River river in modern Albania to Istria in the west and to the Sava river in the north....
The praetorian prefecture of Illyricum was one of four large praetorian prefectures into which the Late Roman Empire was divided. The administrative centre of the prefecture was initially Sirmium, and after 379 Thessalonica....
