Pontus, ancient district in northeastern Asia Minor (in what is now Turkey) on the Black Sea, or Pontus Euxinus, from which it received its name, and extending from Paphlagonia on the west to Armenia on the east. Its southern limits were the Anti-Taurus Mountains, and its territory corresponded to the modern Trabzon and Sivas, Turkey. The name Pontus does not occur in records before the 4th century BC and did not come into common use until after the time of Alexander the Great of Macedonia.
Before Alexander's conquest of Persia in 330 BC, Pontus was governed by a satrap for the Persian Empire. The foundation of the powerful kingdom of Pontus was laid by Mithridates I Ctistes (died about 301 BC). His son, Mithridates II (died about 265 BC), gained control of Paphlagonia and northern Cappadocia. The most important king of Pontus was Mithridates VI. On his overthrow in 66 BC by the Roman general Pompey the Great, the kingdom was divided, the western portion being joined to the province of Bithynia in a Roman province known as Pontus and Bithynia and the eastern region being assigned to native princes. The eastern territory was constituted a Roman province in 62 AD and at first was joined to Galatia, but in the 4th century AD, under the Roman emperor Constantine the Great, it became a separate province with the name
Pontus Polemoniacus.