"Semitic" is a linguistic term, applying to a whole range of langauges across the Middle East, Arabic being the most widely spoken. It's got nothing particularly to do with Palestine or what is now Israel, except that one of the languages in the linguistic group was Hebrew and another was Aramaic, used by the Jewish inhabitants if that area in ancient time.

So "Semite" means people who speak Semitic languages, or whose ancestors spoke them. And most people who fall into that categorey are Arabs, all the way from Morocco to Iraq. "Arabs and Bedouins were not Semites" is in fact completely wrong.

I think the research Rowan would be referring to may have come up with evidence indicating that Palestinian Arabs are to a very large extent descended from those Jews of ancient Palestine who were able to remain there at the time when many others were compelled to leave in the First Century.