'Border' in the Bible

‘Today you are going to cross the border of Moab at Ar.

Jair, a descendant of Manasseh, took over the entire region of Argob as far as the border of the Geshurites and Maacathites. He called Bashan by his own name, Jair’s Villages, as it is today.

and I gave to the Reubenites and Gadites the area extending from Gilead to the Arnon Valley (the middle of the valley was the border) and up to the Jabbok River, the border of the Ammonites.