The Xerons were a peaceful people whose weapons had been inferior to those of their conquerors. The Moroks committed genocide against the Xerons, killing them all except for the children, who were kept as labourers. Most worked in the museum constructed by the Moroks on Xeros until they were transferred to other planets in the empire.
When the First Doctor, Ian Chesterton, Barbara Wright and Vicki Pallister arrived on Xeros, a group of Xeron rebels captured the Doctor, hoping to explain their predicament and earn his help. However, the Doctor managed to escape from them. Vicki helped the Xerons break into the Morok armoury. With new weapons, they killed all the Moroks, taking back their planet. (TV: The Space Museum)