From BiblePortal Wikipedia

International Standard Bible Encyclopedia [1]

kān ( הקּתן , ha - ḳayin  ; the King James Version Cain ): A town in the hill country of Judah (  Joshua 15:57 ). There is, too, apparently a reference to this place in  Numbers 24:21 ,  Numbers 24:22 : "And he looked on the Kenite, and took up his parable, and said, Strong is thy dwelling-place, And thy nest is set in the rock. Nevertheless Kain shall be wasted, Until Asshur shall carry thee away captive."

This place has been very doubtfully identified as the ruin Yukı̄n , a place on a lofty hill Southeast of Hebron, overlooking the wilderness of Judah; the tomb of Cain is shown there. See Pef , III, 312, Sh Xxi .