Kommentar zu Divrej Hajamim I 11:16

and a Philistine governor was then in Bethlehem for they had already taken Bethlehem and stationed a governor therein, who judged [the region]. This was at the beginning of his reign, for the Philistines were still ruling over them, for so we find that prior to David’s arrival, they ruled over Israel in the days of Samson and Samuel, as it is written (I Samuel 4:9): “Strengthen yourselves and be valiant, Philistines, lest you serve the Hebrews, etc.”