What exactly happened to the world that made it like it was? What exactly tanspired before the events of Fallout Equestria happened?

Just a small little thing I did, might not be very good, but I tried.

The O.C. mark is for the narrator since nopony is directly mentioned in the story, besides the princesses.

Yes, this is short. I wrote it up in like 30 minutes, criticism would be appreciated.