The Roman castellum at the Limes Arabicus was probably built at the end of the 3rd/beginning of the 4th century as one of the military camps and forts erected or expanded under Emperor Diocletian (ruled 284 to 305) to protect the eastern border and the trade routes from Arabia to Syria and Palestine.
Kastron Mefa'a had to guard the hinterland of the border and an important outer road alternative to the Via Nova Traiana against attacks by nomadic tribes. Historical sources mentioned that a unit of the Roman army was stationed on the edge of the desert at Mefa'a in the 4th century AD.
"…the Limes was not only the political border between two mighty empires, but also a social and cultural 'internal border' between the deeply Hellenised settled populations living in towns and villages and the semi-nomadic pastoralists inhabiting the semi-deserted steppe known as the Badiya, a border area into which new groups of Arab tribes migrated from Yemen and the Hijaz during Late Antique period." (Ignacio Arce)
When the East Roman / Byzantine Empire gave up more and more bases at the Limes Arabicus, from the 5th century onwards, and had the border region protected by allied Christian Ghassanids, this garrison was also demilitarized. Within the walls, a densely built civil settlement was developed, which gradually abolished the originally rectangular layout of paths and buildings.
The castron is a 158 m x 139 m square with a 2 m thick wall and towers at the corners. To the north and south were the two main gates. After excavations and allocations of stones, architectural structures were made visible and some of the arches were rebuilt. Within the walls there are four churches, including the twin churches with mosaic floors on the eastern wall (end of 6th cent.).
Eusebius of Cesarea mentioned that a unit of the Roman army was stationed on the edge of the desert at Mefaat in the 4th century AD. (Onomasticon 128, 21).
Also the Notitia Dignitatum, a state handbook or auxiliary book of the Roman Empire for the internal use of Roman authorities from the 5th centrury AD, stated that auxiliary cavalry troops of the Roman army were stationed in the camp of Mefaa under the command of the Dux Arabiae.
Romans, Ghassanids and Umayyads and the transformation of the Limes Arabicus: from coerciveand deterrent diplomacy towards religious proselytism and political clientelarism.
In: Limina / Limites Archeologie, storie, isole e frontiere nel Mediterraneo (365-1556) 1. La Transgiordania nei secoli XII-XIII e le ‘frontiere’ del Mediterraneo medievale.
BAR International Series 2386, 2012. Archaeopress, Oxford.