Toros Mountains, which are mostly impassable (except for the Sertavul Pass), may be the reason of the name, was first documented in the 12th century by Sejukid Turks. They used the name only for the Göksu River valley. But soon it became the name of a wider territory. According to an official map drawn by Vital Cuinet the east border of İçil was Alata River and the west border was an unidentified river just to the east of Alanya (may be Dim River). The northern border followed the summit line of the mountains.