Strabo Geography 12.4.3

[3] Continuous with the Astacene Gulf is another gulf, which runs more nearly towards the rising sun than the former does; and on this gulf is Prusias, formerly called Cius. Cius was razed to the ground by Philip, the son of Demetrius and father of Perseus, and given by him to Prusias the son of Zelas, who had helped him raze both this city and Myrleia, which latter is a neighboring city and also is near Prusa. And Prusias restored them from their ruins and named the city Cius “Prusias” after himself and Myrleia “Apameia” after his wife. This is the Prusias who welcomed Hannibal, when the latter withdrew thither after the defeat of Antiochus, and who retired from Phrygia on the Hellespont in accordance with an agreement made with the Attalici. ¹ This country was in earlier times called Lesser Phrygia, but the Attalici called it Phrygia Epictetus. ² Above Prusias lies a mountain called Arganthonium. And here is the scene of the myth of Hylas, one of the companions of Heracles who sailed with him on the Argo, and who, when he was going out to get water, was carried off by the nymphs. And when Cius, who was also a companion of Heracles and with him on the voyage, returned from Colchis, he stayed here and founded the city which was named after him. And still to this day a kind of festival is celebrated among the Prusians, a mountain ranging festival, in which they march in procession and call Hylas, as though making their exodus to the forests in quest of him. And having shown a friendly disposition towards the Romans in the conduct of their government, the Prusians obtained freedom. Prusa is situated on the Mysian Olympus; it is a well governed city, borders on the Phrygians and the Mysians, and was founded by the Prusias who made war against Croesus. ³