Isk'Kahr was a settlement on the planet Vulcan. Before the Vulcan Reformation, the Healers along with his mother T'Leia demanded that Surak remained in isk'Kahr rather than join the rest of the clan that battled on the Ishaya plains. However, he had twisted out of his mothers grasp and raced away to find his father. (TNG novel: The Devil's Heart) Presumably, it was the home of Surak before he had adopted a life of logic though LUG sources state he lived in ShiKahr though its possible he had moved there after the event of the Ishaya plains.