ad mekom Shechem - until the place of Shechem
This traversing of the land by Avraham and his moving away towards a mountain of which the Torah (v8) speaks as well as the fact that he established his tent (residence) between a place called Ai and a place known as Beit-El are all references to matters and places which acquire significance for the Jewish people later on in our history. At this time, these places had not been known by the names reported here in the Torah. This is what the Sages (Tanchuma Lech Lecha 9) had in mind when they said, "Experiences in which the Patriarchs were involved him served as a preview of things that would occur in the lives of their descendants."