Sion, a titular see in Asia Minor, suffragan of Ephesus. No civil document mentions it. It is numbered among the suffragans of Ephesus in the Greek “Notitiae episcopatuum”, from the seventh to the thirteenth century. [See Gelzer in “Abhandlungen der k. bayer. Akademie der Wiss.”, I. Cl. XXI Bd. III Abth. (Munich, 1900), 536, 552; Idem, “Georgii Cyprii descriptio orbis romani” (Leipzig, 1890), 8, 62; Parthey, “Hierocles Synecdemus e Notit. gr. episcopat. (Berlin, 1866), 61, 103, 155, 167, 203, 245.] The names of only three bishops of Sion are known: Nestorius, present at the Council of Ephesus, 431; John, at the Council in Trullo, 692; Philip, represented at Nicaea, 787, by the priest Theognis (Le Quien, “Oriens christianus”, I, 721). This author asks if Basil, Bishop poleos `Asaion represented at Chalcedon, 451, by his metropolitan does not belong to Sion; it is more likely that he was Bishop of Assus. Ramsay (“Asia Minor“, 105) thinks that Sion is probably the same town as Tianae, or Tiarae mentioned by Pliny, V, 33, 3, and Hierocles, 661, 8, and Attaca, mentioned by Strabo, XIII, 607; but this is very doubtful. In any case the site of Sion is unknown.