Ancient and medieval
The city was founded as by Miletan traders (traditionally in 756 BC). It was one of a number (about ten) of Milesian emporia or trading colonies along the shores of the Black Sea. Others include Sinope, Abydos and Cyzicus (in the Dardanelles). Like most Greek colonies, the city was a small enclave of Greek life, and not an empire unto its own, in the later European sense of the word. Early banking (money-changing) activity is suggested occurring in the city according to a silver drachma coin from Trapezus in the British Museum, London.
Trebizond's trade partners included the Mossynoeci. When Xenophon and the Ten Thousand mercenaries were fighting their way out of Persia, the first Greek city they reached was Trebizond (Xenophon, Anabasis, 5.5.10). The city and the local Mossynoeci had become estranged from the Mossynoecian capital, to the point of civil war. Xenophon's force resolved this in the rebels' favor, and so in Trebizond's interest.
The city was added to the kingdom of Pontus by Mithridates VI Eupator and it became home port for the Pontic fleet.
When the kingdom was annexed to the Roman province of Galatia in 64–65, the fleet passed to new commanders, becoming the Classis Pontica. Trebizond gained importance under Roman rule in the 1st century for its access to roads leading over the Zigana Pass to the Armenian frontier or the upper Euphrates valley. New roads were constructed from Persia and Mesopotamia under the rule of Vespasian, and Hadrian commissioned improvements to give the city a more structured harbor. A mithraeum now serves as a crypt for the church of Panaghia Theoskepastos in nearby Kizlara, east of the citadel and south of the modern harbor. The city was pillaged by the Goths in 258, and, although it was afterwards re-built, Trebizond did not recover until the trade route regained importance in the 8th to 10th centuries; 10th century Muslim authors note that Trebizond was frequented
