Africa to the southwest, the Mediterranean to the northwest, Mesopotamia to the northeast, Arabia to the southeast, and far beyond, the ports along the Persian Gulf and Indian Ocean.
Even the authors on the study had assumed that they were following some sort of a unified path, but they found that they were actually moving in a more generalized northeast direction.
Instead of just saying, well, we will go north because I have decided north, you are saying, well, I have a duty now to explain to you the rationale why north and why not northeast.