Byzantium or Byzantion was an ancient Thracian settlement and later a Greek city in classical antiquity that became known as Constantinople in late antiquity which is known as Istanbul today. The Greek name Byzantion and its Latinization Byzantium continued to be used as a name of Constantinople sporadically and to varying degrees during the thousand year existence of the Byzantine Empire. Byzantium was colonized by Greeks from Megara in the 7th century BC and remained primarily Greek-speaking until its conquest by the Ottoman Empire in AD 1453.

The Thracians were an Indo-European speaking people who inhabited large parts of Southeast Europe in ancient history. Thracians resided mainly in Southeast Europe in modern-day Bulgaria, Romania and northern Greece, but also in north-western Anatolia in Turkey.