Roman Emperor Diocletian and the Byzantine ruler Justinian I strengthened the eastern border of the Roman Empire, also known as the Eastern Limes. The western piedmont of Jebel Bishri is partly limited by Strata Diocletiana, i.e., the Diocletian Road, a defensive line with milestones, castra and castella. Strata Diocletiana defended the desert-steppe border of Rome against nomadic tribes and the Parthians, later the Persians.
A Syrian Antiquities Department excavation house, which served as the base camp for the Finnish team in 2000, is situated next to Qasr al-Hair, possibly site of the ancient Adada. A line of fortresses and military posts associated with Strata Diocletiana guard the western plateau: from Sukhna through Taiba (ancient Oriza?) and El-Kowm to Resafa/Sergiopolis and Sura. On the northern edge along the Euphrates there exists the line of forts between Sura and Halabiya, the Castle of Zenobia, through Tibne to Tabus and Qreiye before Deir ez-Zor.
The Roman forts that are present in the Euphrates side of Jebel Bishri have apparently been planned and organised in a way that they functioned together as a defensive system against the Parthians and later against the Persians. The visibility between the forts was much better than that between the military posts in the Strata Diocletiana on the western piedmont of Jebel Bishri. The edge of the mountain especially at Tabus with a small fort was a prominent point to survey and guard the traffic in the river valley.
The Finnish project has delineated ancient road lines with bridges along the Euphrates, of which some offer links between the Roman forts. A. Poidebard assumed the lining of the ancient Roman road, but did not provide any evidence. One of the roads discovered by the Finnish project is cut into marble and the other paved with marble or gypsum. The rock-cut road has horizontal grooves and wheel marks, and extends several kilometres inward to the desert-steppe environment on the mountain. The alignment of the paved ancient road which in its eastern end has altering layers of MacAdam and asphalt, can be detected in the CORONA satellite photographs. Roman pottery has been found in association with both roads, but it is possible that the road climbing to the mountain was already used by Assyrians.
A road beneath the Roman-Byzantine fort of Tabus. Photo: Eivind Seland 2004 © SYGIS – Jebel Bishri, the Finnish Project in Syria
A ruined Roman bridge between the villages of Ayyash and Ain Abu Jima in the northern ridges of Jebel Bishri along the Euphrates. Photo: Minna Lönnqvist 2005 © SYGIS – Jebel Bishri, the Finnish Project in Syria