For the whole of its existence, the province would remain a bone of contention between the Romans and their eastern neighbors, the Sassanid Persians, suffering heavily in the recurrent Roman–Persian Wars. War broke out after the death of the Roman emperor Decius in 251 and the province was invaded by the Persians. In the second half of the 250s, the Persian shah Shapur I (r. ca. 240–270) attacked the Roman east, which was defended by the Roman emperor Valerianus (r. 253–260), whom he captured at Edessa in 260.[2] In the next year however, Shapur was heavily defeated by Odaenathus of Palmyra and driven out of Osroene and Mesopotamia.[3]
It was taken and retaken several times. Being a province on the frontier it had a Roman legion stationed there, Legio III Parthica and its Castrum (homebase) was Resaena though there are some doubts on that fact.
Map showing the Eastern Roman provinces, including Osroene, in the 5th century.
Keser-Kayaalp, Elif; Drijvers, Hendrik J. W. (2018). "Edessa". The Oxford Dictionary of Late Antiquity. Vol. 1. Oxford: Oxford University Press. pp. 516–518. ISBN978-0-19-256246-3.
As found in the Notitia Dignitatum. Provincial administration reformed and dioceses established by Diocletian, c. 293. Permanent praetorian prefectures established after the death of Constantine I. Empire permanently partitioned after 395. Exarchates of Ravenna and Africa established after 584. After massive territorial losses in the 7th century, the remaining provinces were superseded by the theme system in c. 640–660, although in Asia Minor and parts of Greece they survived under the themes until the early 9th century.
