Atarbius is recognised as bishop of Neocæsarea, partly on the evidence of the Codices Coislinanus and Medicæus, which describe him as of Neocæsarea, partly on a comparison of Letters lxv. and cxxvi., addressed to him, with the circumstances of the unnamed bishop of Neocæsarea referred to in Letter ccx. Moreover (cf. Bp. Lightfoot, D.C.B. i. 179) at the Council of Constantinople he represented the province of Pontus Polemoniacus, of which Neocæsarea was metropolis. On the authority of an allusion in Letter ccx. sec. 4, Atarbius is supposed to be a kinsman of Basil.