Limes Arabicus
The Limes Arabicus was a desert frontier of the Roman Empire, running north from its start in the province of Arabia Petraea. It ran northeast from the Gulf of Aqaba for about at its greatest extent, reaching northern Syria and forming part of the wider Roman limes system. It had several forts and watchtowers. The reason of this defensive limes was to protect the Roman province of Arabia from attacks of the nomadic tribes of the Arabian desert. The main purpose of the Limes Arabicus is disputed; it may have been used both to defend from Arab raids and to protect the commercial trade routes from robbers. Next to the Limes Arabicus Emperor Trajan built a major road, the Via Nova Traiana, from Bosra to Aila on the Red Sea, a distance of . Built between 111 and 114 AD, its primary purpose may have been to provide efficient transportation for troop movements and government officials as well as facilitating and protecting trade caravans emerging from the Arabian Peninsula. It was completed under Emperor Hadrian. Fortification During the Severan dynasty (AD 193–235), the Romans strengthened their defences on the Arabian frontier. They constructed several castra (forts) at the northwest end