Joshua 15:11-15

Then the border proceeded to the side of Ekron northward. And the border turned to Shikkeron and continued to Mount Baalah and proceeded to Jabneel, and the border ended at the sea.

The western border was at the Great Sea, even its coastline. This is the border around the sons of Judah according to their families.

Now he gave to Caleb the son of Jephunneh a portion among the sons of Judah, in accordance with the command of the Lord to Joshua, namely, Kiriath-arba, Arba being the father of Anak (that is, Hebron).

And Caleb drove out from there the three sons of Anak: Sheshai, Ahiman, and Talmai, the children of Anak.

Then he went up from there against the inhabitants of Debir; now the name of Debir previously was Kiriath-sepher.