At the very beginning of the whole series, the first Piccolo
was sent to Earth with the wish to become a Kami and create some Dragon Balls
on Earth. This Piccolo needed to get rid of his evil side so he split and
formed the good Kami and the evil Piccolo Daimaou. They are still the same
person so if one dies so does the other.
Kami created Shenron and the Earth Dragon Balls. He becomes the Earth guardian
from the start of Dragon Ball until the Android saga in DBZ.
Piccolo Daimaou shows up near the end of Dragon Ball and is evil. He creates
some children which are called Piano, Tamborine, Cymbal and Drum to help him
fight. They are soon killed and just before Piccolo Daimaou dies he spits
out another egg containing the Piccolo which we all know from DBZ.
This Piccolo is the reincarnation of Piccolo Daimaou. He is a fighter and
is basically the same person as his father. He has the same link with Kami,
so Kami is still alive. This Piccolo has a large role in DBZ. He helps Goku
kill Raditz and trains Gohan when he is little. Gohan and Piccolo become good
friends, although Piccolo is still one of Goku's rivals. Piccolo stays as
a Z warrior on Earth. In the Freeza saga he fuses with Nail to gain more power.
In the Android saga he re-fuses with Kami to get stronger, and Dende becomes
the new Earth Guardian.
