Even from the mount Halak, that rises up toward Seir, even unto Baalgad in the valley of Lebanon below mount Hermon: and all their kings he took, and struck them, and slew them.
Read Chapter 11
Augustine of Hippo
AD 430
It is asked how this can be true, since the Hebrews were not altogether able to capture all the cities of those seven nations either in the times after the judges or in the times of the kings. But one must understand it to mean that Joshua never approached any city with hostile intent that he did not capture. Or it may mean that no city remained uncaptured except for those which were in the regions mentioned above. For those regions were enumerated in which there were cities concerning which the conclusion was made: “and he captured all of them in war.” - "Questions on Joshua 17"
And part. Hebrew, "from Mount Halak, (Haydock; or the bald mountain, destitute of wood) going up to Seir, (which is very shady; that is, from the southern parts of Chanaan, by Seir) as far as Baal gad "on the east side of the Jordan, perhaps unto Coelosyria. (Calmet)