The history of Uterio's World seems to have been more or less identical to the main BZPBverse up until the Battle of Mordor, where Klak was defeated by Uterio Di Armechio. ZFT decided to withdraw from the Rebel Alliance, leaving the Malchiorians to fight Uterio alone.
Emboldened by the victory, Uterio's forces attacked Malchior IV again. Nadle led the defenders, but he was drawn into a trap by Jarvis and killed. With all the big-hitters out of the equation, and ZFT unwilling to intervene, Uterio easily conquered the planet, and had RacKoon City destroyed with nuclear weapons to scare the population into submission. Serecio was installed as the governor of the planet, and under his rule thousands of people were driven into refugee camps. An army of robots called Omnidroids, designed by Jarvis, was released on the planet to crush any pockets of resistance. Despite all this, a small resistance movement continued to function.
For the full list of Uterio's World natives, see the category.