[SunkenCiv]

Not sure, although I’m inclined to think AD, Roman era, even though it was over 1000 years old by 400 AD.

https://en.wikipedia.org/wiki/Ordu#History

https://en.wikipedia.org/wiki/Ordu#Archaeology

Periplus of the Euxine Sea by Arrian of Nicomedia (ref to its ancient name, Cotyora)
https://topostext.org/work/203

§ 23 From the Thermodon to the river Beris ninety stadia. From the Beris to the river Thoaris sixty stadia. From Thoaris to Oenoe thirty stadia. From Oenoe to the river Phigamus forty stadia. From Phigamus to the fortress of Phadisana one hundred and fifty stadia. From Phadisana to the city of Polemonium ten stadia. From Polemonium to the promontory called the Jasonian an hundred and thirty stadia. From the Jasonian promontory to the island of the Cilices fifteen stadia. From this island to Boona, where there is a port for ships, seventy-five stadia. From Boona to Cotyora ninety stadia. Xenophon mentions Cotyora as a city, and says, that it was a colony of the Sinopians: at present it is no more than a village, and that not a large one. From Cotyora to the river Melanthius is, at the utmost, sixty stadia.

[Verginius Rufus]

Xenophon mentions Cotyora in Anabasis 5.5.3, where he calls it a Greek city. The immediately preceding passage about the Mossynoeci (Mossynoikoi) is very interesting--he calls them the most barbaric of all the peoples the Ten Thousand encountered and the furthest removed from Greek customs. Among other things, the Mossynoeci wanted to have sex in public with the courtesans accompanying the Greek army.