David and his men went up, and made a raid on the Geshurites, and the Girzites, and the Amalekites; for those [nations] were the inhabitants of the land, who were of old, as you go to Shur, even to the land of Egypt.
Actually he was wiping out a lot of these little Philistine villages, and Canaanite villages and making out to king Achish that he was fighting against Judah.