Intact arches of the West Church, Umm el Jimal.
After the Romans turned the Nabataean Kingdom into their Provincia Arabia, they also occuppied Umm el-Jimal. In A.D. 180, the Roman imperial authorities constructed a wall and a gate, a large reservoir and the Praetorium. During the 4th century A.D., in response to the rebellion of Zenobia of Palmyra, Roman armies allied with the Arab Tanoukhid Federation restored order in a destructive military campaign. At Umm el-Jimal the civilian settlement was replaced by a military garrison stationed in a purpose built fort, the early castellum, which was part of the general fortification of the Roman frontiers at the time of Diocletian and Constantine. Besides this castellum structures on the sight included the Great Reservoir, the Praetorium and a small temple.
A gradual transformation from a military station to a civilian town began as Roman imperial power waned and was then replaced by the Byzantine era. From the 5th to 8th centuries, Umm el-Jimal became a prosperous rural farming and trading town. During this period of prosperity, many residents converted to Christianity resulting in an explosion of church construction: Fifteen churches were built in the late 5th and 6th centuries. The population of Umm el-Jimal likely grew to between 6,000 and 8,000 people during this time. Evidence of this culture is found throughout the site in the form of Christian symbols on houses and churches. Paradoxically, Umm el-Jimal's age of rural prosperity came after the strictures of Roman occupation were lifted.
Umm el-Jimal’s local agricultural culture continued after the Muslim conquest and under the Umayyad caliphs during the 7th century. Though the site decreased in size, some new construction took place. This construction included private houses, possible conversion of several structures into mosques, and the remodeling of the Praetorium with frescoed walls and mosaic floors. Around this time the population decreased, especially after an earthquake hit Umm el-Jimal in A.D. 749.