Which preposition to use with kaf

by Occurrences 1%

Malik Shah Bal then asked if any king or chief was absent, and if all were arrived; the jinns answered, "Mighty sire, all are present except one named Musalsal Jadu, who has erected a fort on the mountain Kaf by the means of magic; he, from haughtiness, is not come, and we, your majesty's slaves, are not able to bring him by force; the place is strong, and he himself also is a great devil.

in Occurrences 1%

But Vathek replied civilly, but decisively, that he was taking Nouronihar with him; and the princess, having heard her declare that she would follow him beyond the Kaf in the land of the Afrits, was appeased, and pronounced Nouronihar a girl of both courage and science.

Which preposition to use with  kaf