What is "kageras"

Kageras is a late medieval era fort in Sudan. Located in Upper Nubia, it lies on the eastern side of the Nile, about half way between the third and second cataract. During the tenth or eleventh century, a church was built here. A defensive wall was added in the late Middle Ages. The wall was once about high and is still well preserved. On every corner, there are round towers. In the north, there is an entrance. It is doubtful whether this wide site was inhabited continuously. It appears to be more like a refuge for Christian from attacking nomads. A 1966-1969 American - Swiss expediiton examined the site.