Mr. Satan dies. The King of Earth honors him with a national funeral.
To avenge their fallen leaders, the remnants of Frieza's soldiers invade Earth raining destruction and wreaking havoc throughout the world.
After losing their leaders, Frieza's army collapsed. However, the guard troops that served under Frieza and his father's direct command remained persistent in their hopes to avenge them and waited for a chance to invade Earth.
Because they had not been present at the time of Frieza and his father's death, the guard troops knew nothing of the existence of Goku, Future Trunks or the others. So, after they investigated the Earth, the soldiers assumed that the "Earth's Strongest Man", Mr. Satan, had been the one who killed Frieza. Knowing they'd be unable to handle anyone strong enough to defeat Frieza, they decided to leave Earth alone so long as Mr. Satan was around.
After learning of Satan's death, they proceed with their invasion of Earth. The Earth’s Royal Army attempted to counterattack, but all fail.
The Earth is faced with a crisis due to chubby aliens.
Having researched Earth ahead of time, Frieza's remnants invade the planet with a chubby species of alien impervious to both guns and standard martial arts techniques. Martial artists fighting against these aliens are beaten back; they are saved by Goten and Trunks, who put their "Kikoukenjutsu" fighting style into practice. With their influence, the "Swordsman" class is born.
West City, the home of King Cold and Frieza's killer, Trunks, becomes a main target. Realizing the danger, Bulma works out a way to store the entire city inside a capsule for safekeeping.
At this time, Majins from all over the world who had lost their homes in the destruction were protected within the city. Some of them decided to stay, even after the battle, and started to develop their own unique, Majin culture in West City.
With the Earth in crisis, the heroes of the past gather at Master Roshi's place in order to eradicate the remnants of Frieza's soldiers.
The ones who ultimately defeat the Frieza's soldiers are Krillin, Tien Shinhan, and their comrades—the heroes of the past. In order to hide their identities, the warriors put on Saiyaman-like costumes, but their ki-based fighting style still becomes a hot topic and global interest in "ki" escalates.
Incidentally, at this time Tien Shinhan is 87 years old, Krillin is 84, Gohan is 63, Trunks is 54, Goten is 53, and Pan is 41.