Diocletian engaged in a major military expansion in the region, building a number of castella, watchtowers, and fortresses along the fringe of the desert just east of the Via Nova. This line of defence extended from south of Damascus to Wadi al-Hasa. The region from Wadi Mujib to Wadi al-Hasa contained four castella and a legionary camp. The frontier south of Wadi al-Hasa, which extended to the Red Sea at Aila (Aqaba), may have been called the "Limes Palaestina". In this region, ten castella and a legionary camp have been identified. The term may have referred to a series of fortifications and roads in the northern Negev, running from Rafah on the Mediterranean to the Dead Sea, or to the region under the military control of the "dux Palaestinae", the military governor of the Palaestinian provinces.