Cyrenaica was a Roman province on the northern coast of Africa between Egypt and Numidia; it had been formerly Greek. That area is now the eastern part of the Mediterranean coast of Libya. The province consisted classically of five cities, the Pentapolis Cyrene (near the village of Shahat) with its port of Apollonia (Marsa Susa), Arsinoe (Tocra), Berenice (Benghazi) and Barca (Merj) of which the chief was the eponymous Cyrene. In the south Cyrenaica faded into the Sahara.

Conquered by Alexander the Great, it passed to the Ptolemies, then to Rome. It was separated from the main kingdom by Ptolemy VIII and given to his son Ptolemy Apion, who, dying without heirs in 96 BC, bequeathed it to the Roman Republic.

Although some confusion exists as to the exact territory Rome inherited, by 78 BC it was organised as a province with Crete, until the reforms of Diocletian in 300 changed all of the provincial administrations.