Although a large part of the planet's surface was badly damaged, the causality was less than Raditz's group had expected. In fact, even though many Yardratians were badly hurt or even killed by the Ginyu Force. The truth was that most of them were clones, so only about a dozen Yardratians had died as opposed to the thousands the group had thought.
Elder Souma taught Raditz their techniques to purge the impurities in one's spirit. And according to Elder Souma, Goku and Piccolo did not have many impurities in their spirit, and they had tempered their spirits quite well already. Gohan did not even have the slightest impurity in his spirit but he had not started tempering his spirit.
Elder Souma personally taught the three their special meditation technique to temper their spirit.
Raditz not only had plenty of impurities in his spirit, but he also had never tempered his spirit. But first things first, he had to purge the impurities to some degree before he should start tempering his spirit. The only good thing was that Raditz's spirit was much bigger and stronger than other's, which Raditz realized probably had to do with him fusing with the old Raditz's soul.
Elder Souma presumed Raditz had a mutated soul, a stronger and bigger spirit had a much higher starting point. Although he was riddled with trouble right now, once he managed to purge the impurities, Raditz's spirit would gain much more and much faster while doing the same amount of spirit training.
Thankfully, Elder Souma was one of the best in Spirit Control. Because Raditz had never trained his spirit, for him to purge the impurities on his own was very challenging for him. Elder Souma might not be able to fully purge all the impurities, but when there are so many impurities, he is able to at least scrape off the impurities on the surface.
For one month, Raditz had to endure the pain from having his spirit stabbed by thousands of needles and his impurities extracted from his spirit. The pain was nothing like physical pain which Raditz had gradually gotten more used to, especially after his body almost broke apart from his fight with Turles. The pain Raditz felt was directly from his mind and spirit. It was like his brain was stabbed repeatedly in thousands of spots every single time. It was like his soul was being stabbed and pulled apart.
Raditz was screaming from the top of his lungs every single day. If other's heard his scream, they would have thought Elder Souma was torturing Raditz. But Elder Souma seemed to have expected this and had brought Raditz to stay in an isolated room.
After that one month, Elder Souma had removed roughly 50% of all the impurities, but it only meant that the fewer impurities one had, the harder it was to remove the remaining impurities. But the remaining 50% impurities was no longer possible to be removed with Elder Souma's help, and only Raditz himself could slowly purge the remaining impurities.
After one torturous month, Raditz was finally relieved that he no longer needed to endure that soul-rending pain. Because, although Elder Souma had taught Raditz how to purge impurities so as to have Raditz quicker learn the technique after Souma let him experience it. But in order to actually use this technique, Raditz needed to temper his spirit until he had a certain level of control over his spirit.
The basic to tempering one's spirit was to meditate in order to calm one's mind and spirit to achieve harmony. Naturally, those with fewer impurities in their spirit was able to achieve harmony much quicker.
Once one achieved harmony in mind and spirit, one can generate an intangible will like cloth that is used to grind and hone the spirit carefully. If careless, instead of tempering one's spirit, it can get damaged from grinding too hard like a cloth getting ripped into pieces.
Thus, meditation was a slow and long process that required plenty of patience.
Luckily, the Yardratians were weak and only good at one thing, and that one thing was Spirit Control, their spirit tempering techniques were of a much higher level than Earth's. By spending the same amount of time to temper their spirit, their gains were more than threefold more.
Thankfully, after having half of his impurities removed, Raditz was able to achieve harmony of mind and spirit and slowly generate his own will into a cloth. And because his spirit was much bigger and stronger, not only could he fold out the will cloth to hone a larger area of his spirit at the same time, he could also grind harder since it was much stronger. Thus, spending the same amount of time tempering his spirit, Raditz was finally able to experience what talent means.
Piccolo had incredible willpower and patience, maybe due to the majority of his training consisting of meditation to improve his Ki. Piccolo was the first to reach the qualified level in spirit to learn Instant Transmission. Although Piccolo was able to make clones and gigantify himself, after learning Yardratian's clone and gigantification techniques, his own clone, and gigantification techniques had improved greatly.
Goku had a great foundation as well, all thanks to Kami's teachings since Goku was a kid. After spending 6 months tempering his spirit, Goku was finally qualified to learn Instant Transmission.
Maybe because it was not a combat-related skill, it took Goku 6 months to barely learn it.
Gohan was earnestly tempering his spirit, under Raditz's advice, Gohan also took some time to train in the Gravity Chamber to fully take advantage of his Saiyan blood.
Raditz had fully experienced his advantage of having a much bigger and stronger spirit. After spending 6 months tempering his spirit, his gains were equal to 10 times that of Earth's normal training. That is to say, the 6 months Raditz spent tempering his spirit was equal to 60 months of normal training which was equal to 5 years of training.
After the group had stayed for 7 months, Raditz was also qualified to learn Instant Transmission. Maybe because of his spirit being bigger and stronger, or maybe because Raditz had a solid learning foundation from being a college student before transmigrating to the Dragon Ball World. It only took him 2 months to learn Instant Transmission.
Raditz also tried to learn Healing, Clone, and Gigantification. But Healing was a much more advanced technique that even Piccolo did not manage to learn after trying to learn it for 6 months. Raditz spent 3 months learning Clone and Gigantification and decided to leave the Healing for another time.
The group had stayed on Planet Yardrat for a whole year now and was getting weary of the life here. Of course, they did not forget to celebrate little Gohan's 6th year birthday.
It was now Age 764, March. The group wanted to teleport to Earth in order to save the 3 months traveling time by spaceship. But they were unable to sense anyone's Ki from Earth due to the long distance. Raditz then proposed to teleport to King Kai, and then teleport back to Earth. Because King Kai's planet was located in the Other World, the distance was non-existent, it was simply located in a different dimension. Thus the group was able to sense King Kai's Ki and teleport to him, and then teleport to Earth.
Raditz remembered how Gohan's lack of real battle experience had him directly challenge Jeice and would have ended up dead if he was alone. But neither he nor Goku had the heart to be cruel to a 6 year old kid. Thus, Raditz decided to have Piccolo train Gohan. It was also a chance for the two of them to get close to each other like in the original storyline.
Piccolo left for the mountains to go back to his own training. Raditz followed Goku and Gohan back to their home.
Chichi welcomed everyone warmly and immediately questioned them about their trip. They brought some Yardratian clothes, food and other souvenirs for Chichi and talked about their trip in space. Though they left out about Gohan being badly hurt by Jeice, afraid Chichi would go crazy. They also told Chichi about the Yardratian's culture, technologies, and knowledge they had experienced. Of course, they left out that they spent the majority of their time there training.
After spending a few days at home, Raditz told Goku about his plan to let Piccolo train Gohan. It might be some distance away from their home to Piccolo, but for those who could fly, it was a negligible distance. And for them who had learned Instant Transmission, it was merely a moment away.
Goku really liked Piccolo and agreed to let him train Gohan, he felt Piccolo was very smart and mature and suitable to teach Gohan. They grabbed Gohan and after locking on to Piccolo's Ki, they teleported over to him.
Piccolo wasn't very agreeable, but after Gohan had also personally persuaded him, he reluctantly agreed to train Gohan.
"Brat, don't regret your decision. Once the training starts, there's no backing out." Piccolo said seriously to Gohan.
"Umu, uncle Piccolo, don't worry! I'll train hard!" Gohan nodded seriously.
Raditz decided to stay over and spar with Piccolo, and also to avoid an angry Chichi once she learns that Gohan will be staying away to train in martial arts.
Goku waved goodbye and teleported back home and got an earful from Chichi. Yet he never understood Raditz had purposefully avoided the crossfire by not coming back home for some time.