The Purpose of Limes Arabicus
el Lejjun
Historians debate the purpose of these defenses. S. Thomas Parker has vigorously defended the traditional theory, which says that the Romans were concerned about raids by nomadic Arab tribes called Saracens on settlements and caravan traffic. He has collected literary and circumstantial evidence that shows the Romans were concerned about attacks from Saracen invaders. The forts and watchtowers were strategically located at the entrances to wadis, which provided the easiest access to the settlements and cities to the west. The limes was not intended as a barrier against nomadic invasion but as a monitoring system of their movements and a deterrent to raiding.
David Graf has been the primary critic of this position. He argues that gaps in the line of defense suggest that the Romans were not concerned about raids from the desert. Instead, he proposes that they were concerned with pacifying a potentially rebellious population. This theory has several problems. First, the military installations were located on the fringe of the desert rather than in the villages and cities where the people lived. Second, he provides little evidence that the population in Provincia Arabia was rebellious. Third, the gaps in the line of defense often occur in areas of rough terrain, which would provide a natural defense against invaders from the east. Fourth, he discounts the literary evidence for the threat of Saracen invasion.
Philip Mayerson has also argued that the limes was not a border or a line of defense designed to keep out the enemy known as the Saracens. Saracens lived and moved freely within the province, not only outside its margins. Many raids may have originated within the province. He prefers to think of the limes as the land that forms the furthest extent of a country's settled or inhabited region. Forts were manned with garrisons of mounted troops that protected lines of communication and trade. They were not designed to control the movement of tribes but to react defensively to attacking forces. They monitored the movements of tribes to provide early warning of attacks and provided refuge for the settled population during raids.
Benjamin Isaacs has offered another theory. He thinks the Romans were concerned with brigands and robbers who were disrupting commerce. While this may have been one of the concerns of the Romans, the expense and effort of establishing so many defenses suggests a greater threat to the Romans than Isaacs proposes. Also, his theory would suggest the presence of military garrisons in the major population centers and along interior roads, but such evidence is lacking. Instead, military posts were located in the desert or close to the desert fringe. Therefore, Parker's theory seems to provide the most adequate explanation of the limes Arabicus. However, the forts may have served different purposes in different periods, and they may have served more than one purpose much of the time.