The desert tribes had been the enemies of Israel for centuries and had intermittently raided Israelite communities adjacent to the desert.

 Earlier, when Saul “utterly destroyed” all the Amalekites (ch. 15:8), it is likely that many of them disappeared into the desert, and in a short time reappeared to continue their raids. The wandering Bedouin peoples have a mysterious way of disappearing suddenly, only to reappear in time. The statement that David “left neither man nor woman alive” refers, of course, only to those residing in the communities he attacked. The one way to bring permanent peace to the border towns of Israel was to drive these tribes back so far into the desert that they would hesitate to return. It was almost impossible to exterminate them. They lived on loot secured through guerrilla warfare, and much of the stock and other supplies David captured upon this occasion had probably been taken from Israelite communities in the first place.