After the division of the Roman Empire in 395, Sinope remained with the Eastern Roman Empire. Its history in the early Byzantine period is obscure, except for isolated events: it was used by Justinian II as a base from which to reconnoitre Cherson, participated in the rebellion of the Armeniac Theme in 793, was the site of Theophobos' proclamation as emperor by his Khurramite troops in 838, and suffered its only attack by the Arabs in 858.
