Iraq is culturally and linguistically Arab, but ethnically (majority) Aramaic. So I have read anyway; I lack the time or the courage to do the field research. The territory was indeed part of the Persian empire for a time.
Iran remains culturally, linguistically and ethnically descended from the Persians.
Of course these are over-generalizations. Iraq in particular has been trampled over so many times by various warring empires that it has one of the most diverse populations in the Middle East.
-Glenn
PS what happened to the TP argument?