Matthew Poole and continuators on Numbers 13:29

29 The Amalekite dwelleth in the land of the south : and the Hittite, and the Jebusite, and the Amorite dwelleth in the mountains : and the Canaanite dwelleth by the sea , and by the coast of Jordan.

Where we are to enter the land, and they who were so eager and fierce against us that they came into the wilderness to fight with us, will without doubt oppose us when we come close by their land and are about to settle in their neighbourhood, the rather, to revenge themselves for their former loss and shame received by us. Therefore they mention them, though they were no Canaanites.

(i. e.) In the mountainous country in the South-east part of the land, so that you cannot enter there without great difficulty both because of the noted strength and valour of those people, and because of the advantage they have from the mountains.

Not the midland Sea, which is commonly understood by that expression, but the salt or dead sea, as appears, 1. because it is that sea which is next to Iordan, as here follows: 2. because the Canaanites dwelt principally in those parts and not near the mid-land sea. So these guard the entrance on the east-side, as the others do on the South.