Targum zu Dewarim 32:8

When the Most High made allotment of the world unto the nations which proceeded from the sons of Noach, in the separation of the writings and languages of the children of men at the time of the division, He cast the lot among the seventy angels, the princes of the nations with whom is the revelation to oversee the city, even at that time He established the limits of the nations according to the sum of the number of the seventy souls of Israel who went down into Mizraim.

When the Most High divided the nations by lot, and distinguished the languages of the children of men, He appointed the bounds of the peoples according to the number of the tribes of the Beni Israel.