Ancient Greek city states
Byzantion
Byzantion was the original ancient settlement on the Thracian Bosphorus (the strait between the Black Sea and the Sea of Marmara). This is the site of the present-day Turkish city of Istanbul.
Byzantium was founded in 667 BC and due to its strategic location it was one of the most important cities of the time, controlling all trade with the Black Sea, Europe and Asia.
Byzantium played an important role in the Greco-Persian Wars. The city was occupied by the Persian king Dareios I, but in 478 BC it was liberated by the Greek army and became an ally of Athens. When the Peloponnesian War broke out, this alliance was terminated. In 340 BC, the city withstood an attack by King Philip II. Macedon and remained independent. During the Macedonian Wars, Byzantion joined the Roman Empire.
In the following years, Byzantion experienced periods of decline and renewal. In 330 AD, the city was renamed Constantinople. The city became the capital of the Roman Empire alongside Rome itself. Subsequently, it became the capital of the Eastern Roman Empire (otherwise known as the Byzantine Empire = a derivative of the name Byzantion).