It is hard to tell when Acilisene became a bishopric. The first whose name is known is of the mid-5th century: Ioannes, who in 459 signed the decree of Patriarch Gennadius I of Constantinople against the simoniacs. Georgius or Gregorius (both forms are found) was one of the Fathers of the Second Council of Constantinople (553), appearing as "bishop of Justinianopolis". Theodorus was at the Third Council of Constantinople in 681, signing as "bishop of Justinianopolis or the region of Ecclenzine". Georgius was at the Photian Council of Constantinople (879). Until the 10th century, the diocese itself appears in none of the "Notitiae Episcopatuum". At the end of that century, they present it as an autocephalous archdiocese, and those of the 11th century present it as a metropolitan see with 21 suffragans. This was the time of greatest splendour of Acilisene, which ended with the decisive defeat of the Byzantines by the Seljuq Turks at the Battle of Manzikert in 1071. After the 13th century, there is no mention of diocesan bishops of Acilisene and the see no longer appears in "Notitiae Episcopatuum". No longer a residential bishopric, Acilisene is today listed by the Catholic Church as a titular see.