Roman forts on the Arabian frontier
Dr. Gregory Linton
The Meaning of Limes Arabicus
In AD 106 the Romans under Emperor Trajan achieved control of the region east of the Jordan River, which was previously ruled by the Nabataeans. Until then, the Nabataean kingdom had provided a buffer between the Roman Empire and the threat of enemies to the east. Historians do not know how and why the Romans took direct control. Perhaps the lack of a legitimate successor to the deceased Nabataean king resulted in a power vacuum. The Romans annexed the area and called it Provincia Arabia. It was governed by a senatorial legate appointed by the emperor, and its capital was Bostra (or Bosra) in southern Syria. [Map - 184 K]
The Romans took measures to guard the security of the region. Trajan built a major road, the Via Nova Traiana, from Bostra to Aila on the Red Sea, a distance of 267 miles. Built between AD 111 and 114, its primary purpose may have been to provide efficient transportation for troop movements and government officials.
During the Severan dynasty (AD 193-235), the Romans strengthened their defenses on the Arabian frontier. They constructed several forts at the northwest end of the Wadi Sirhan, and they repaired and improved roads.
Milestone on a Roman Road
Around AD 300, Diocletian partitioned the old province of Arabia by transferring the southern region to the province of Palestine. Later in the fourth century, the southern region was detached from Palestine as a separate province, which eventually was called Palaestina Tertia. Each province was administered by a praeses with civil authority and a dux with military authority.
Diocletian engaged in a major military expansion in the region, building a number of forts (castella), watchtowers, and fortresses along the fringe of the desert just east of the Via Nova. The term used for this north-to-south line of military installations is limes Arabicus, which means "Arabian frontier." This line of defense 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 zone south of Wadi al-Hasa was called the limes Palaestina, which extended to the Red Sea at Aila ('Aqaba). In this region, ten castella and a legionary camp have been identified.
Parker estimates that the early fourth-century garrison of Arabia totaled only about 4,850 men and was reduced by 1,000 men by the end of the century. The military buildup may account for the dramatic increase in Byzantine settlements in the fourth and fifth centuries.
The only literary evidence for Roman military operations in Arabia is the Notitia Dignitatum, which was written around AD 400. It lists two legions, eight elite cavalry vexillations (equites), six cavalry units (alae), and five infantry cohorts under the command of the dux Arabiae. These forces were referred to as limitanei, troops that manned the limes. Of these twenty-one units, the location of only four have not yet been identified.