The place most closely connected with St. Basil's early years is neither Caesarea nor Neocaesarea, but an insignificant village not far from the latter place, where he was brought up by his admirable grandmother Macrina.  In this neighbourhood his family had considerable property, and here he afterwards resided. The estate was at Annesi on the river Iris (Jekil-Irmak),  and lay in the neighbourhood of scenery of romantic beauty. Basil's own description  of his retreat on the opposite side of the Iris matches the reference of Gregory of Nazianzus  to the narrow glen among lofty mountains, which keep it always in shadow and darkness, while far below the river foams and roars in its narrow precipitous bed.
There is some little difficulty in understanding the statement of Basil in Letter CCXVI., that the house of his brother Peter, which he visited in 375, and which we may assume to have been on the family property (cf. Letter CX. S: 1) was "not far from Neocaesarea." As a matter of fact, the Iris nowhere winds nearer to Neocaesarea than at a distance of about twenty miles, and Turkhal is not at the nearest point. But it is all a question of degree. Relatively to Caesarea, Basil's usual place of residence, Annesi is near Neocaesarea. An analogy would be found in the statement of a writer usually residing in London, that if he came to Sheffield he would be not far from Doncaster. 
 Epp. cciv., ccx., ccxxiii.
 Epp. iii., ccxxiii. The researches of Prof. W. M. Ramsay enable the exact spot to be identified with approximate certainty, and, with his guidance, a pilgrim to the scenes of Basil's boyhood and earlier monastic labours might feel himself on fairly sure ground. He refers to the description of St. Basil's hermitage given by Gregory of Nazianzus in his Ep. iv., a description which may be compared with that of Basil himself in Ep. xiv., as one which "can hardly refer to any other spot than the rocky glen below Turkhal. Ibora," in which the diocese Annesi was situated, "cannot be placed further down, because it is the frontier bishopric of Pontus towards Sebasteia, and further up there is no rocky glen until the territory of Comana is reached. Gregory Nyssenus, in his treatise on baptism" (Migne, iii. 324 c.) "speaks of Comana as a neighbouring city. Tillemont, thinking that the treatise was written at Nyssa, infers that Nyssa and Comana were near each other. The truth is that Gregory must have written his treatise at Annesi. We may therefore infer that the territory of Ibora adjoined that of Comana on the east and that of Sebasteia on the south, and touched the Iris from the boundary of Comana down to the point below Turkhal. The boundary was probably near Tokat, and Ibora itself may have been actually situated near Turkhal." Prof. W. M. Ramsay, Hist. Geog. of Asia Minor, p. 326.
 Ep. xiv.
 Greg. Naz., Ep. iv.
 On the visits to Peter, Prof. W. M. Ramsay writes: "The first and more natural interpretation is that Peter lived at a place further up the Iris than Dazimon, in the direction of Neocaesarea. But on more careful consideration it is obvious that, after the troubles in Dazimon, Basil went to take a holiday with his brother Peter, and therefore he did not necessarily continue his journey onward from Dazimon. The expression of neighbourhood to the district of Neocaesarea is doubtless only comparative. Basil's usual residence was at Caesarea. Moreover, as Ibora has now been placed, its territory probably touched that of Neocaesarea." Hist. Geog. of A.M. p. 328.
Reference address : https://www.elpenor.org/basil/life-works.asp?pg=3