How can the border go from Beis Kel to Luz? They are the same place (Bereishis 28:19)!
Radak: This is not the same Beis Kel; Yakov was in Beis Kel of Binyamin, which is also Luz
Bi'ur ha'Gra: Yakov called three places Beis Kel - (a) What was Luz, he called Beis Kel; (b) He built a Mizbe'ach, and called the place Kel Beis Kel; (c) After Hashem blessed him, he called the place Elokim Beis Kel (Bereishis 28:19, 35:7,15). The last one is mentioned also in Shmuel 1 10:3.
Where is Luz with respect to Beis Kel?
Malbim: It is opposite Har Beis Kel, but to the south of it. [It says regarding Binyamin's border] "v'Hayu Totz'osav Midbarah Beis Aven; v'Avar mi'Sham ha'Gevul Luzah."
What is "Gevul ha'Arki"?
Malbim: It is the long border with Binyamin, north of Binyamin.
Below (verse 5), it lists Atros on the eastern border!
Malbim: That is another Atros.
