It is very dificult to conduct a sane discussion with people who elevate the palestinian Arabs to a separate ethnic group. They are just plain Arabs.

This shows a tremendous amount of ignorance (and I would suggest, prejudice) about Arabs. The above quote is like saying Scottish and Welsh are not separate ethnic groups, they're just British.

It appears that the ethnic Philistines (aka Palestinians) left with the Jews and followed Mose. The current unhappy folks who spend all their energy trying to destroy Israel go back no father than the period of Islamic conquests around 700 AD.

This is false. You can't use the bible as an historical document in this case. In this case, at least, it's just a fiction. Genetic studies have shown that the people who are now called Palestinians and the Arab Jews originated in that very area (what is now Israel and occupied Palestine), with some extra genetic material provided by people passing through the area, since it was an important crossroads of civilization, and are more related to each other than they are to any other groups.

What came more recently to the region, and is probably what pdq is referring to, is the Arab language and the religion of Islam. But the people who are now referred to as the Palestinians are indigenous to the region.

What pdq and other people who use these kind of lies are doing is denying a people their history, and that is cultural genocide.