and the border went up to Debir from the valley of Achor, and so northward, looking toward Gilgal, that is over against the ascent of Adummim, which is on the south side of the river; and the border passed along to the waters of En Shemesh, and the goings out of it were at En Rogel;
Ancient Near Easterners used natural landmarks (rivers, mountains, deserts, towns, etc.) to construct borders as well as artificial boundaries that they made by drawing lines between sites. Virtually all nations have used these methods, and they are still common today.