Jamieson, Fausset and Brown on Numbers 34:3-5

3-5. your south quarter--The line which bounded it on the south is the most difficult to trace. According to the best biblical geographers, the leading points here defined are as follows: The southwest angle of the southern boundary should be where the wilderness of Zin touches the border of Edom, so that the southern boundary should extend eastward from the extremity of the Dead Sea, wind around the precipitous ridge of Akrabbim ("scorpions"), thought to be the high and difficult Pass of Safeh, which crosses the stream that flows from the south into the Jordan--that is, the great valley of the Arabah, reaching from the Dead to the Red Sea.