What do we include from "Es Kol ha'Aretz"?
Malbim: Everything in the southern border.
What is the meaning of "Negev"?
Malbim: It is a dry place. Metzudas Tziyon: The Targum of "Charvu Pnei ha'Adamah" (Bereishis 8:13) is "Nagvu". Also below, [Kalev's daughter] complained "Eretz ha'Negev Nesatani [give to me springs]!" (15:19).
What are "ha'Ashedos"?
Rashi: It is where water of the hills pours. 1 Malbim - just like ha'Shefelah is the opposite of ha'Har, ha'Ashedos is the opposite of ha'Negev; it is Eshed ha'Nechalim" (Bamidbar 21:14, i.e. inclines along which streams flow - Ramban).