Map of the Roman Empire - Oea

Oea
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Ancient Oea A Roman city in the province of Africa, former Sidonian colony. The modern name is Tripoli.

Oea. A city on the northern coast of Africa with a mixed population of Libyans and Sicilians. Under the Romans it was a colony with the name Aelia Augusta Felix ( Hist. iv. 50). It is perhaps the same as the modern Tripoli. - Harry Thurston Peck. Harpers Dictionary of Classical Antiquities. New York. Harper and Brothers. 1898.

Oea. The city was founded in the 7th century BC, by the Phoenicians, who gave it the Libyco-Berber name Oea (or Wy't)[3], suggesting that the city may have been built upon an existing native town. The Phoenicians were probably attracted to the site by its fine natural harbor, flanked on the western shore by the small, easily defendable peninsula, on which they established their colony. The city then passed into the hands of the rulers of Cyrenaica (a Greek colony on the North African shore, east of Tripoli, halfway to Egypt). It was wrested away from the Greeks by the Carthaginians, like Tripoli, another Phoenician colony.

By the later half of the 2nd century BC it belonged to the Romans, who included it in their province of Africa, and gave it the name of Regio Syrtica. Around the beginning of the 3rd century AD, it became known as the Regio Tripolitana, meaning "region of the three cities", namely Oea (i.e. modern Tripoli), Sabratha and Leptis Magna. It was probably raised to the rank of a separate province by Septimius Severus, who was a native of Leptis Magna.

In spite of centuries of Roman habitation, the only visible Roman remains, apart from scattered columns and capitals (usually integrated in later buildings), is the Arch of Marcus Aurelius from the 2nd century AD. The fact that Tripoli has been continuously inhabited, unlike e.g. Sabratha and Leptis Magna, has meant that the inhabitants have either quarried material from older buildings (destroying them in the process), or built on top of them, burying them beneath the streets, where they remain largely unexcavated. - Wikipedia

Oea
OEA (Pomp. Mela, 1.7.5; Oeensis civitas, Plin. Nat. 5.4; Tac. Hist. 4.50; Solin. 27; Ammian. 28.6; ??a, Ptol. 4.3.12), a town in the district of the Syrtes, which, with Leptis Magna, and Sabrata, formed the African Tripolis. Although there had probably been an old Phoenician factory here, yet, from the silence of Scylax and Strabo, the foundation of the Roman colony ( �Oeea colonia,� Itin. Anton.) must be assigned to the middle of the first century after Christ. It flourished under the Romans until the fourth century, when it was greatly injured by the Libyan Ausuriani. (Amm. Marc. l.c.) At the Saracen invasion it would seem that a new town sprung up on the ruins of Oea, which assumed the Roman name of the district--the modern Tripoli; Tr�blis, the Moorish name of the town, is merely the same word articulated through the medium of Arab pronunciation. At Tripoli there is a very perfect marble triumphal arch dedicated to M. Aurelius Antoninus and L. Aurelius Verus, which will be found beautifully figured in Captain Lyons Travels in N. Africa, p. 18. Many other Roman remains have been found here, especially glass urns, some of which have been sent to England. For some time it was thought that a coin of Antoninus, with the �epigraph� COL. AVG. OCE., was to be referred to this town. (Eckhel, vol. iv. p. 131.) Its right to claim this is now contested. - Dictionary of Greek and Roman Geography (1854) William Smith, LLD, Ed.