Cyrenaica (sĭrənāˈĭkə, sĪrə–) [key], historic region, E Libya, bordering on the Mediterranean Sea. Benghazi, Al Marj, Darnah, and Tobruk are the chief cities. The Greeks colonized N Cyrenaica in the 7th cent. B.C., founding numerous settlements. In the mid-1st cent. B.C., Cyrenaica became a Roman province. In A.D. 115–16 there was a large-scale but unsuccessful revolt of Jewish settlers. When Rome was divided (4th cent.) into the Eastern and Western empires, Cyrenaica came under the Byzantines, who, however, exercised little control over the region. In 642 Arab armies conquered Cyrenaica and many Arabs settled in the region from the 9th to 11th cent. The Ottoman Turks captured the area in the mid-16th cent. The Sanusi Muslim brotherhood was founded (1843) in Cyrenaica and gained many adherents there. For the history of Cyrenaica after the Ottoman conquest, see Libya.