The oldest military fortification in the Timok region, Timacum Minus, was built in the Beli Timok valley, near the village of Ravna, not far from Knjaževac. Archaeological investigations of this locality indicated the continuity of settlement from prehistoric times to the Middle Ages.

This settlement reaches its peak in the period of Antiquity as Timacum Minus represents an important mining and metallurgical center. Timacum Minus is located at the place where the roads to the Danube, Pomoravlje, Adriatic, and Aegean seas crossed.