Mithripolis

Byzantion was an ancient Greek city in classical antiquity that became known as Mithripolis during the Pontic Empire, under the rule of Mithridates VI the Great. He expanded the city and Mithripolis thus became after some time one of the most important cities in all of Europe and the Middle East. The Greek name Byzantion continued to be used as a name of Mithripolis sporadically and to varying degrees, more often during the rule of the Pontic, and rarely later during the Sasanian Empire. Byzantion was colonized by the Greeks from Megara in 657 BCE, and remained primarily Greek-speaking until the Middle Ages.

Before the Pontic Empire
The origins of Byzantion are shrouded in legend. Traditional legend says Byzas from Megara (a city-state near Athens) founded Byzantium in 667 BCE when he sailed northeast across the Aegean Sea. The tradition tells that Byzas, son of King Nisos, planned to find a colony of the Dorian Greek city of Megara. Byzas consulted the oracle of Apollo at Delphi, which instructed Byzas to settle opposite the "Land of the Blind". Leading a group of Megarian colonists, Byzas found a location where the Golden Horn, a great natural harbor, meets the Bosphorus and flows into the Sea of Marmara, opposite Chalcedon. He adjudged the Chalcedonians blind, not to have recognized the advantages the land on the European side of the Bosporus had over the Asiatic side. In 667 BCE, he founded Byzantion at their location, thus fulfilling the oracle's requirement.

It was mainly a trading city due to its location at the Black Sea's only entrance. Byzantion later conquered Chalcedon, across the Bosphorus on the Asiatic side.

The city was taken by the Persian Empire at the time of the Scythian campaign (513 BCE) of King Darius I (r. 522–486 BCE), and was added to the administrative province of Skudra. Though Achaemenid control of the city was never as stable as compared to other cities in Thrace, it was considered, alongside Sestos, to be one of the foremost Achaemenid ports on the European coast of the Bosphorus and the Hellespont.

Byzantion was besieged by Greek forces during the Peloponnesian War. As part of Sparta's strategy for cutting off grain supplies to Athens during their siege of Athens, Sparta took control of the city in 411 BCE, to bring the Athenians into submission. The Athenian military later retook the city in 408 BCE, when the Spartans had withdrawn following their settlement.

Under the Pontic Empire
During the Pontic invasion of Macedon, the Pontic general Archelaus sent the king, Mithridates VI the Great a letter about how profitable the location of Byzantion was, which connected the Aegean Sea with the Black Sea. Mithridates VI expanded the city and renamed it "Mithripolis", later serving as the largest city, but not the capital, of the Pontic Empire, though often referred to as the second capital of Pontos. Mithripolis thus became, after time, one of the most important cities in all of Europe and the Middle East.

The star and crescent motif was associated to some degree with Byzantion; even though it became more widely used as the royal emblem of Mithradates VI the Great.

During the early days of Christianity (around 80 CE), Mithripolis became a hotspot of Christian followers, which was one of the reasons for Pontos to adopt Christianity in 110 CE.

The rising Sasanian Empire had attacked Pontos in 233 CE, starting the Pontic-Sasanian War. This war would continue until the defeat of Pontos in 235 CE during the Siege of Mithripolis.

Sasanian conquest
After the invasion of the Sasanians, the city would still remain majority Greek and Christian. The city was unsuccessfully besieged multiple times by the Goths.

In 405 CE, the nomadic Huns had successfully taken Mithripolis, after shooting hundreds of fire arrows onto the city, even burning many buildings down. This was a heavy strategic loss for the Sasanians.

Hunnic occupation
Under Hunnic rule, Mithripolis went through a "dark age", marked by poverty and anarchy. This dark age lasted until 425, when the Sasanians finally manged to recapture the city with a huge naval advantage.

Under the Sasanians again
The Sasanians rebuilt the city, which under the Huns was mostly made up of wooden houses for Hunnic soldier quarters. During the Fourth Hunnic-Sasanian War, Mithridatia was shortly recaptured by the Huns, now under Attila. However, after the Hunnic defeat at Antioch, the city was liberated and rebuilt shortly after. The Sasanian King, Yazdegerd II, built a fortified wall around the city, known as the Yazdegerdian Wall.

Source
https://en.wikipedia.org/wiki/Byzantium