The legend of the Super Saiyan God was mentioned for the first time during the Battle of Gods movie. Beerus, who was In a long sleep, had a dream, which told him about a Super Saiyan God who would challenge him to. However, soon, thanks to the Dragon Balls, Shenron mentioned that a Super Saiyan God can be created if five pure-hearted Saiyans poured their Ki into another pure-hearted Saiyan. The first person to ever become a Super Saiyan, and start the legend of the Super Saiyan was Yamoshi. He was a Saiyan, who along with his 5 other Pure hearted Saiyan friends, fought against the evil Saiyans. When cornered, he was able to transform into Super Saiyan. This actually made him the first Super Saiyan ever. The other Saiyans, seeing his strength, were shocked. However, because he drained his energy, and the number of the opposing Saiyans was just too great, he was defeated and he ultimately died, along with his five other friends. This power became a legend, and hence, even way ahead in time, people like Freeza were extremely afraid of the story of the Legendary Super Saiyan. He was a mere Super Saiyan. Ultimately, it was Goku who became the Super Saiyan God after 5 pure-hearted Saiyans transferred their Ki into him. Goku is the first known person to become the Super Saiyan God, and Veeta is the second. All Yamoshi did was create the concept behind the Super Saiyan God when he and his friends were killed. It soon became a legend, passed down from generation to generation. After that, Goku became the first person to achieve this form, and he did so in his fight vs Freeza. In this form, Freeza was absolutely no match for Goku. After that, some more Saiyans, like Vegeta and Gohan got this form. At that time, Gohan was the youngest Super Saiyan ever. However, soon came Trunks and Goten, and both of those kids achieved this Legendary form very quickly. It is as simple as that. Since at that time, it was believed that the Super Saiyan transformation can only be achieved through rage and extreme emotion. But, Toriyama himself has cleared that up. Basically, most of the fans had it all wrong. There are several other factors that come into play, according to Akira Toriyama. According to Toriyama, not every Saiyan can become a Super Saiyan, even if they have extreme rage and go through severe training, which shuns the common belief. The actual transformation into a Super Saiyan depends on several factors, one of which is the S-cells. Once these S-cells reach a certain amount, one can then use anger, and increase the amount of the S-cells, hence turning into a Super Saiyan. Now, how were Goten and Trunks able to transform into Super Saiyan without any serious rage?
