One of the most surprising characteristics of Iran and the Iranian people is the profound and widespread hatred of Arabs despite the massive religious, cultural and linguistic influences that this group has had on Iran. There is a general feeling that the backwards tribal Arabs who invaded Persia were nothing in comparison to the great Persian civilization that had lasted for millenia. In spite of having very Arabic origins, Twelver Shi'ism (the Islam of the Islamic Republic) is considered as an Iranian development. A look into Iranian history can show many examples of clashes between the Persians and the Arabs.