When did Persians bacome Arabs?

Have you seen the "Crash" ? Wow, watch it. several times ! think about it. Talk about it. Feel it.
When did persian become arabs? what's wrong with arabs? what's wrong with blacks?
I am persian. I could undrestand the message of the movie.
I'll try to be more careful about my attitude toward my other friends.
Crash is one of the best movies I've ever seen.
Anyways, When did PERSIAN become ARABS? Nothing is wrong with being arab. NOTHING, but I have my own culture. I respect to other culture.
Please call me PERSIAN.
Read what Roger Ebert says about the movie.