The fortifications on Trajan Mountain and Mok Hill were probably built in the early iron age and continously used during ancient and medieval periods. It probably could be identified with the town Diabolis which was an important base for the wars of Basileus IV the Bulgar Slayer in his wars against the Greater Bulgarian Empire. Maybe Alexios I Komnenos also used it in his wars agains the Normans of Robert Guiscard in 1108. The fortification was probably abandoned in the late medieval age in favour of the newly founded town of Voskopoja.