well the most characters of Dragonballz lives there like goku krillin tien master roshi and more.
the race that lives on planet earth is the human.
Planet Vegeta
This is the planet where saiyans come from.
the planet was named after the king Vegeta.
Frieza was always alittle afraid of the saiyans thinking that they wil become his future enemy so he killed them al and destroyed the planet. the saiyans where already slaves of frieza. The only saiyans that survived where Goku Nappa Vegeta and radits and bardock.
Planet Namek
This was the planet you saw in the frieza saga when he was have the dragonballs and wish for inmortality. then gohan bulma and krillin go there to get the dragonballs.
the eldest namek is guru. piccolo and kami are also from planet namek. but the planet got destroyed by frieza so they later get transported to a new planet namek.
