Kaf

According to Arabian tradition, a great mountain that stretches to the horizon on every side. The earth is in the middle of this mountain, like a finger in the middle of a ring. Its foundation is the stone Sakhrat, the least fragment of which is capable of working untold marvels. Sakhrat, made of a single emerald, is said to cause earthquakes. Kaf, which is frequently referred to in Eastern tales, is said to be the habitation of genii. To reach it one must pass through dark wildernesses, and it is essential that the traveler be guided by a supernatural being.