Water, Communication, Sight, and the Location of Fortifications on the Strata Diocletiana (Syria) in Late Antiquity

Abstract The Strata Diocletiana was a military road in Late Roman Period Syria. It ran from Damascus to the Euphrates by way of Palmyra. The road was fortified and received its name during the reign of Diocletian (284–305 CE), following the Roman sack and subsequent garrisoning of Palmyra after the city’s failed revolt 272–273 CE. The Strata Diocletiana is only one of several attested routes between Palmyra and western Syria and one of two between Palmyra and Damascus. In this study, we seek to understand why this route was chosen for the new fortified road. We compare the location of Late Roman fortifications along the Strata Diocletiana to the modern distribution of water in the Syrian Desert and the theoretical least-cost paths between Palmyra and Damascus, and Palmyra and the fortress of Sura on the Euphrates. The argument is made that some parts of the Roman road network in the Syrian Desert were planned in order to control major water sources along the desert rim, but that the new military road between Damascus and Palmyra in the late third century CE was constructed with the aim of monitoring and controlling access to settled regions from the desert, in addition to ease and speed of communication. The conclusions have bearings not only on our understanding of the Late Roman defence and communication system, but also on nomad-settled interaction in Late Antiquity and the use of GIS methodologies in the reconstruction of ancient communication networks.