John Limbert explains the ancient grudges between Iran and its neighboring nations:
Mutual ignorance compounds the hostility [between Iranians and Arabs]. Despite centuries of interaction and contact, neither side knows much about the other. What do Arabs and Iranians know of each other's art, literature, history, politics, and traditions? Very little. Perhaps a close parallel is the relations between Mexicans and Americans. As Americans we appreciate Mexican food (or a variety of it) and Mexican music. But what do most of us know of Mexico's culture and history? Very little indeed. So in this mutual ignorance it is easier to dismiss the others as "liars," "snakes," and "heretics" than make the effort required for understanding.
His bottom line on the prospect of a new regional war, as urged by the neocons:
Do the Arabs really want a war with Iran? Probably not, given the potentially disastrous economic and political consequences of such a conflict. But with all their pent-up grievances, both ancient and recent, they are not above sharing frustration, particularly with those American visitors who might -- for very different reasons -- share their feelings of hostility.