Giresun's history goes back to the late 6th century BC, when it was founded by Greek colonists from Sinope, 110 km east of the homonymous city founded by Pharnakes I of Pontus, using citizens transferred from Kotyora, ca 180 BC. The name of the city is first cited in the bookAnabasis by Xenophon as Kerasus. Historic records reveal that the city was dominated by theMiletians, Persians, Romans, Byzantines and Empire of Trebizond. The older parts of the city lie on a peninsula crowned by a ruined Byzantine fortress, sheltering the small natural harbour. Nearby is Giresun Island, in ancient times called Aretias, the only major Black Sea island in Turkish territory. According to legend, the island was sacred to the Amazons, who had dedicated a temple to the war god Ares here. Even today, fertility rites are performed here every May, now shrouded as a popular practice, but really a 4,000 year old celebration. During the medieval period Kerasunt was part of the Byzantine Empire and later the second city of the Empire of Trebizond. From 1244 onwards the Seljuk Turks moved into the area, pursued at times by the Mongol hordes until in 1461 the whole of this coast was brought within the Ottoman Empire by Sultan Mehmet II. She was shortly occupied by Emirate of Hacıemiroğlu (Emirate of Chalybia) between 1398-1400.
The victory of Alexios II over the Turkmen ‘Koustoganes" at Kerasus in September 1301 was vitally important. If Kerasus had fallen in 1301, the Turkmen would have obtained major access to the sea and the days of the Trapezuntine Empire would have been numbered. After 1301, Alexios II built a fortress which overlooks the sea.
4.2 km east-northeast of Kerasus is a fortified island called Ares (Αρητιας νήσος or Αρεώνησος). It was here according to Apollonius of Rhodes, that the Argonauts encountered both the Amazons and a flock of vicious birds. The Greeks of the island held out against the Ottomans for 7 years after the fall of Trapezus 1461.