Dacia Inferior in 158 by Antoninus Pius. Divided into three provinces (Tres Daciae) in 166 by Marcus Aurelius: Porolissensis, Apulensis and Malvensis (imperial procuratorial provinces). Abandoned by Aurelian in 271. AD 103/114 - Epirus Nova (in western Greece and southern Albania), Epirus was originally under the province of Macedonia. It was placed under Achaia in 27 BC except for its northernmost part, which remained part of Macedonia. It became a separate province under Trajan, sometime between 103 and 114 AD, and was renamed Epirus Nova (New Epirus) (imperial procuratorial province). AD 114 – Armenia, annexed by Trajan, who deposed its client king. In 118 Hadrian restored this client kingdom AD 116 – Mesopotamia (Iraq) seized from the Parthians and annexed by Trajan, who invaded the Parthian Empire in late 115. Given back to the Parthians by Hadrian in 118. In 198 Septimius Severus conquered a small area in the north and named it Mesopotamia. It was attacked twice by the Persians (imperial praefectorial province). AD 116 – Assyria, Trajan suppressed a revolt by Assyrians in Mesopotamia and created the province. Hadrian relinquished it in 118. Under Septimius Severus AD 193 – Numidia, was separated from Africa Proconsularis by Septimius Severus (imperial propraetorial province). AD 194 – Syria Coele and Syria Phoenice, Septimius Severus divided Syria into these two units in the north and the south respectively. Imperial provinces (proconsular and propraetorial respectively). Under Caracalla AD 214 – Osrhoene, this kingdom (in northern Mesopotamia, in parts of today's Iraq, Syria and Turkey) was annexed. Under Aurelian AD 271 – Dacia Aureliana (most of Bulgaria and Serbia) created by Aurelian in the territory of the former Moesia Superior after his evacuation of Dacia Trajana beyond the River Danube. Many of the above provinces were under Roman military control or under the rule of Roman clients for a long time before being officially constituted as civil provinces. Only the date of the official formation of the province is marked above, not the date of conquest. Later Roman Empire Emperor Diocletian introduced a radical reform known as the tetrarchy (284–305), with a western and an eastern senior emperor styled Augustus, each seconded by a junior emperor (and designated successor) styled caesar. Each of these four defended and administered a quarter of the empire. In the 290s, Diocletian divided the empire anew into almost a hundred provinces, including Roman Italy. Their governors were hierarchically ranked,