When last we convened, we were pondering the matter of the Ark's effect on the Philistines. It made their idol, Dagon, lose its human head and hands, retaining only its fish torso: merman become ordinary fish. It also caused all the Philistine citizenry to experience extremely painful hemorrohoids, to the point where people were wailing loudly in the streets.
The key to this event, I would posit, lies in the initial encounter of Abraham with the Philistines. It is a basic principle of Biblical exegesis that the experiences of Abraham, Isaac and Jacob on the individual level always presage national experiences of the Jewish People.
We know that Abraham is described as clashing with two specific cultures. Although he lived in Canaan, he occupied territories that had been lying fallow until his arrival, so there is no overt conflict between him and Canaanites. He only once is presented as interacting with a Hittite (a sub-nation of Canaan), when he negotiates to buy a piece of property for a burial plot. Additionally, whatever clashes he may have had with Nimrod and others before being called to go to Canaan are not specified in the Scripture; whatever we know of that period is through oral history, some of which was eventually written into Midrash.
In brief, the Bible chooses to record only the two collisions of weltanschauung, one with Pharaoh, king of Egypt, and one with Abimelech, first identified only as king of Gerar (Genesis 20:2). Later, when Abraham signs a treaty with him, the text (ibid 21:32) identifies his people as being Philistines.
Clearly, these are the two prototypical encounters for the man living the inspired life in the material world. The meeting with the Egyptians; then, the meeting with the Philistines.