Mount Seir — Not that of Edom, but another so called from some resemblance it had to it.
Related Commentaries of Joshua 15:10
Joshua 15:10
10 And the border compassed from Baalah westward unto mount Seir, and passed along unto the side of mount Jearim, which is Chesalon, on the north side, and went down to Bethshemesh, and passed on to Timnah: