When Frieza blew up Planet Vegeta, it couldn't have been that long ago since Goku was born earlier that day, before the extermination of his race... and his planet. Or was he? Who said that the birth of Goku was on the same day as the Genocide of the Saiyans? Anwser me. No one? Correct! Just because it was in the same movie, doesn't mean it was the same day. So the events of DragonBall could have been taking place on Earth, while this was all happening to planet Vegeta. This is my version.