Why are some events in the 1950s to late 1900s left off in 'we didn't start the fire'?

He wasn't trying to write about the entire history of the U.S. and foreign relations... he was just trying to choose certain events he deemed important to his purpose. He wrote the lyrics before the song itself, but there's still the issue of flow that perhaps those events created. Maybe he didn't think of them at the time. Or maybe he had to stop somewhere... I could rattle off a long list of things he *could* have included, but that simply wouldn't have been practical. Whatever the reason, I don't think it's extremely important that they were left out since the events included achieve his goal perfectly fine.