Limes Arabicus

The Limes Arabicus) was a desert frontier of the Roman Empire, mostly in the province of Arabia Petraea. It ran northeast from the Gulf of Aqaba for about 1,500 kilometers (930 mi) at its greatest extent, reaching northern Syria (present-day Rojava) 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 "barbarian" tribes of the Arabian desert. The main purpose of the Limes Arabicus is disputed; it may have been used both to defend from Saracen raids and to protect the commercial lines from robbers.

Next to the Limes Arabicus Trajan built a major road, the Via Nova Traiana, from Bosra to Aila on the Red Sea in Israel, a distance of 267 miles/430 kilometres. 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 Hadrian.