gives this name to the channel which connects the lake and the sea. If the river Cius is not identical with this channel, it must be a small stream near Cius. As Ptolemy speaks of the outlets of the Ascanius, it has been conjectured that there may have been two, and that they may be the Hylas and Cius of Pliny; but the plural ἐκβολαί does not necessarily mean more than a single mouth; and Pliny certainly says that the Ascanius flows into the gulf. However, his geography is a constant cause of difficulty. The position of Cius made it the port for the inland parts, and it became a place of much commercial importance. Pomponius Mela calls it the most convenient emporium of Phrygia, which was at no great distance from it. Cius was taken by the Persians, after the burning of Sardis, in 499 BCE. It joined the Aetolian League, and was destroyed by Philip V of Macedon in the Second Macedonian War (200–197 BCE), and given by him to Prusias I of Bithynia. Prusias, who had assisted Philip in ruining Cius, restored it under the name of Prusias (Προυσιάς). It was sometimes called Prusias ἐπιθαλασσίη, or "on the sea," to distinguish it from other towns of the same name, or πρὸς θάλασσαν. In the text of Memnon the reading is Cierus; but Memnon, both in this and other passages, has confounded Cius and Cierus. But it is remarked that Cius must either have still existed by the side of the new city, or must have recovered its old name; for Pliny mentions Cius, and also Mela, Zosimus, and writers of a still later date. It was an important chain in the ancient Silk Road and became known as a wealthy town. There are coins of Cius, with the legend Κιανων, belonging to the Roman imperial period; and there are coins of Prusias with the epigraph, Προυσιεων των προς θαλασσαν. Cius became an early Christian bishopric. Its bishop, Cyrillus, took part in the First Council of Nicaea in 325, and Theosebius attended the Council of Ephesus. The names of many of his successors in the first millennium are known from extant contemporary documents. At first a suffragan of Nicomedia, it soon became an autocephalous archdiocese, being listed as such in Notitiae Episcopatuum from the 7th century onward. No longer a residential bishopric, Cius is today listed by the