'Frontier' in the Bible

It continued along to Azmon and proceeded to the Brook of Egypt (Wadi el-Arish), and the border ended at the [Mediterranean] sea. This was their southern border.

Then the Israelites heard it said, “Look, the Reubenites, Gadites, and half the tribe of Manasseh have built an altar on the frontier of the land of Canaan at the region of the Jordan, on the Israelite side.”