empire of Trebizond, 1204–1461. When the army of the Fourth Crusade overthrew (1204) the Byzantine Empire and established the Latin Empire of Constantinople, several Greek successor states sprang up. These were the empire of Nicaea, the despotate of Epirus, and the empire of Trebizond. The last of these was founded by two members of the former imperial Comnenus family, David and his brother Alexius I (reigned 1204–22) of Trebizond, who took the titles of Grand Comnenus and emperor, which were assumed by all his successors. The empire comprised the entire southern coastal region of the Black Sea except its westernmost section, which belonged to Nicaea. Trebizond (modern Trabzon), the capital, and Sinope (Sinop) were the chief cities.

The western part of the empire was the conquest of David Comnenus, who soon lost his dominions to Nicaea. The empire of Trebizond was further diminished when Sinope fell (1214) to the Seljuk Turks, and the emperor became a vassal of the sultan of Iconium; for the remainder of its existence Trebizond was restricted to the SE Black Sea coastal region. When the Byzantine Empire was restored (1261) under Nicaean leadership, Trebizond remained separate and independent, although it was often forced to pay tribute to the succeeding dominant powers of Asia Minor.

After the Mongol invasion the empire experienced tremendous economic prosperity. It became the commercial route through Asia Minor, leading into the great trade route to East Asia that the Mongols had opened, and its position on the trade routes from Russia and from the Middle East to Europe furthered its importance. Its commercial life was controlled by the Genoese and the Venetians, and the empire profited much from the added opportunity to export the produce of its own rich hinterland. The empire reached its greatest prosperity under Alexius II (1297–1330).

With the decline of Mongol power after 1320, Trebizond suffered increasingly from Turkish attacks, civil wars, and domestic intrigues. In this period the emperors attempted to gain strength by marrying the princesses of the Comnenus dynasty to Turkish princes. Relations between Trebizond and the Muslims were generally friendly, but after the Turkish conquest of Constantinople (1453), David Comnenus, the last emperor of Trebizond, promoted an alliance of the non-Ottoman Asian states against Sultan Muhammad II. In 1461, Muhammad forced David to surrender. A few years later the sultan had him put to death together with all the Comnenus males but one, and Trebizond was annexed to the Ottoman Empire. At the height of its wealth and power the court of the Grand Comneni was a great artistic and cultural center and made Trebizond the last refuge of Hellenistic civilization.

See studies by W. Miller (1926) and J. Monfasoni (1984).