Cius (/ˈsaɪəs/; Greek: Kίος Kios), later renamed Prusias on the Sea (/ˈpruːʒəs/; Latin: Prusias ad Mare) after king Prusias I of Bithynia, was an ancient Greek city bordering the Propontis (now known as the Sea of Marmara), in Bithynia (in modern northwestern Turkey), and had a long history, being mentioned by Aristotle, Strabo and Apollonius Rhodius. It was colonized by the Milesians and became a place of much commercial importance. It joined the Aetolian League, and was destroyed by Philip V of Macedon in the Second Macedonian War (200-197 BC). It was rebuilt by Prusias I of Bithynia who renamed it for himself. An important chain in the ancient Silk Road, it became known as a wealthy town.

• http://en.wikipedia.org/wiki/Cius