Genesis 21:32

“Thus they made a covenant at Beersheba, etc.] Which took its name from the oath annexed to the covenant there made; and which is observed for the sake of what follows, to show that when they finished their agreement, and the ceremony of it, then Abimelech rose up, and Phichol, the chief captain of his host; from the place where they had been conversing and covenanting with Abraham: and they returned into the land of the Philistines; from Beersheba, which was in the extreme border of it, unto Gerar, which lay in the midst of it, and was the capital city in it; otherwise both places were in Palestine, or the land of the Philistines, a people that came out of Egypt originally, and settled here:…”

“21:32 The Philistines in Genesis are different from the Philistines of Judges through Kings. The earlier Philistines had Semitic names (e.g., Abimelech) and Canaanite culture. The later Philistines were apparently of Greek origin, with Greek customs and culture. They seem to have arrived in Canaan by sea from the Aegean area around 1200 BC, during the time of the judges. Probably the name of the later Philistines was used here simply to describe the region’s earlier inhabitants.”