According to local belief excavation of the churches was started by a group of missionaries known as the ‘Nine Saints’, who arrived in Ethiopia from the Mediterranean region during the fifth or sixth century. Together with their Ethiopian followers these missionaries inspired a long tradition of monasticism, promoting isolation in remote and highly inaccessible locations such as those in which the rock-hewn churches are found. Preferred lithologies for church hewing were Adigrat Sandstone and Enticho Sandstone. The tradition continues up to the present, as rock-hewn churches are still being excavated today.