Vegita is a saiya-jin who came from the planet Vejitta. Freiza destroyed the planet vejitta and all of its people, and the only people who weren't on the planet was: Vegita (who was in Freiza's ship), and a couple more that were unknown. Gokuu was origanaly sent to destroy all life on planet earth, so that he could that he could restart with the race of the siaya-jins, but Gokuu bumped his head and forgot everything when he was real young. When Freiza and his henchman relized that it was too long to not have Gokuu back, so they sent Raditz. Raditz was then defeated by Goku and Piccilo. When he was almost defeated he turned his scouter on so that they could hear what was happening so they sent Vegita and Nappa to see what happened to Raditz. And that is how he is brought up into the story.