The VI century A.D. saw the beginning of the Byzantine – Arab conflict during which time Derinkuyu and its vicinity were heavily attacked three times.
After these attacks many of the Byzantines living in this area found it increasingly difficult to continue living underground in hiding and evacuated Derinkuyu, which thus lost much of its earlier importance.
The underground city was deserted for many years and fell into disrepair. Airducts were blocked by earth and rocks swept into them by rain and wind; many roofs in rooms and tunnels fell in.
After the seventh century Christians were able to carry on the propagation of their religion openly; some of them carved hundreds of churches into the rocks and "fairy chimneys" in the Göreme and So?anl? regions and used them as training centres for Christian missionaries.
After the VII century Anatolia gradually came under the domination of the Seljuk Turks. The religious toleration shown by them gave an opportunity to the Christians in this area to add many frescoes to the churches at Göreme, Ihlara and So?anl?.
In the XIV century, with the emergence of Ottoman power, some more of the Byzantines left the region and thus Göreme, Ihlara and So?anl? lost their early importance, though the natural beauty and artistic interest of the region is unsurpassed in the world.