John Gill Commentary Genesis 15:20

"and the Hittite, and the Perizzite, and the Rephaim," — Genesis 15:20 (ASV)

And the Hittites
Who had their name from Heth, a son of Canaan, see (Genesis 10:15) ; they dwelt about Hebron, in the south of the land of Canaan:

and the Perizzites ;
these dwelt in the wood country of the land, (Joshua 17:15) ; and seem to have their name from dwelling in villages, and at a distance from towns and cities, and were a boorish and uncivilized people, see (Genesis 13:7) :

and the Rephaims ;
or "giants", as the Targums of Onkelos, and Jonathan; they dwelt near the Perizzites, (Joshua 17:15) ; of these see (Genesis 14:5) .