The article discusses the territorial range, structure and political and military part played by the Byzantine administrative unit of Sicily. Created between 687 and 695, it included, apart from the island from which it derived its name, also smaller units, which encompassed southern Italy (with Naples, Malta, Gozo, the Lipari Islands and other lesser islands close to Sicily). Originally, the part performed by the ruling strategi consisted of controlling the loyalty of the Ravenna exarchs and popes, enforced, if the need arose, by armed expeditions. The growth of the Longobard estates and the Arabian conquest of North Africa increased this role. Sicily became the chief administrative centre and military base of the Byzantium in the central Mediterranean, and the local strategi frequently represented Byzantium in diplomatic contacts with the Longobards and, from the eighth century, also with the Franks. The policy of the strategi intended to protect Byzantine influence on the Apennine Peninsula by winning over supporters of the Empire. The Arabian invasion of Sicily in 827 diminished its political significance, and the governors were forced to concentrate on defending the island instead of on wide diplomatic activity.