King Kai explained the story of the Saiyan race to Goku during the Vegeta Saga. He explains that around Age 720, a civil war broke out. The Saiyan Army tried many times to overthrow the Tuffles but were unsuccessful, sparking a ten year conflict on the planet. Although the Saiyans were bigger in size and physically far superior, they were fewer in number compared to the Tuffles. The Tuffles had a trump card in the form of advanced their technology to read the power levels of the Saiyans and advanced weaponry such as blasters to hold them off. Then, around Age 730, the Saiyans were able to transform into Great Apes thanks to the full moon that only appeared once every 8 years on the planet, with this they finally annihilated the Tuffles and had the planet renamed Planet Vegeta after their commanding hero, King Vegeta.
King Kai goes on to explain that after their victory over the Tuffles, the Saiyans were approached by the Arcosians.
These aliens had money and technology, but their planet was unsuitable,
so they hired a group of Saiyans to take over a planet for them and in
return, they would share their technology with them. Over the years, the
Saiyans also learned how to use the Tuffles' advanced equipment and
became smarter and less barbaric, although they still lusted for
fighting and destruction
- Super Saiya-jin Transformations
- Big Bang Ki Attack
- 125% Powerlevel gain bonus