of Pontica, in turn part of the Prefecture of the East. Byzantine Empire Following the Muslim invasions of the 640s AD, the Byzantine Empire reorganized its provincial structure into themes. The province of Bithynia and Pontus was reorganized into the Bucellarian, Opsikion, and Optimatoi themes. See also List of Roman governors of Bithynia and Pontus Kingdom of Pontus Mithridates VI of Pontus Footnotes References Roman provinces in Anatolia Roman Bithynia Roman Pontus Roman Paphlagonia History of the Black Sea 1st-century BC establishments in the Roman Republic 1st-century BC establishments 7th-century disestablishments in the Byzantine Empire Roman client kingdoms ca:Regió de Bitínia#Província romana