basically the brits gave iran a raw deal for their oil - the british navy got it essentially for free and there was a lot of other fuckery involved such that iran was getting completely screwed. then aramco gave the saudis a pretty good deal for their oil, and iran realized just how badly they got screwed. the brits wouldn't budge. so mossadegh nationalized the anglo-iranian oil company (a precursor to BP). churchill was big mad, and started trying to red scare truman. truman wouldn't have any of it (mossadegh fucking hated the communists and truman's secretary of state thought the brit position was that they would have iran's oil or no one would). but allen dulles and john foster dulles were receptive. so when john foster dulles becomes secretary of state under ike, and allen got promoted to CIA director, they started a coup.
if the dulles brothers had told the president of exxon to go give iran the same deal aramco gave the saudis i very much doubt we end up at the same place. iran was not at all friendly with an imperial power just on the other side of the caucasus in the 1800s and early 1900s, and the soviets tried to pull a donbas/transnistria just after WW2.