The border continued to the northern slope of Beth-hoglah and came out at the northern bay of the Salt Sea, at the mouth of the Jordan. This was the southern border.
We have here the lot of the tribe of Benjamin, which Providence cast next to Joseph on the one hand, because Benjamin was own and only brother to Joseph, and was little Benjamin (Psa 68:27), that needed the protection of great Joseph, and yet had a better protector, for the Lord shall cover him all the day long, Deu 33:12.
Commenting on Joshua 18:11-28
And the border passed along to the side of Bethhoglah northward,.... Inclining somewhat toward the north, but not leaving the city to the north, for it is included in the lot of Benjamin, Jos 18:21; of which place see Jos 15:6, and the outgoings of the border were at the north bay of the salt sea; here ended the southern border of Benjamin, even at...
And the border passed along to the side of Bethhoglah northward: and the outgoings of the border were at the north bay of the salt sea at the south end of Jordan: this [was] the south coast. (m) To the very straight, where the river runs into the Salt sea.