Byzantium

From BoardGameGeek:

(from the rulebook:) Byzantium is a game covering the high point of the Byzantine Empire, from the 8th century defeat of the Arabs to the fall of Constantinople in 1204 AD.... Byzantium can be played with up to four players: the Byzantines, the Franks, the Khazars, and the Muslims. Each player represents a single great power or alliance. Players must use a combination of military strength and cunning strategy to maintain and increase their power.