The Korads were the inhabitants of Mechanistria. They were controlled by the machines there.
Biology
The Korads looked identical to humans. (PROSE: Peril in Mechanistria)
Culture
The Korads were led by the Mechanistrians, who were in turn controlled by the machines. Korads generally wore little clothing, only a kilt or shirt and a belt to hold their tools. They were organised into Havens, with Haven One being controlled by the Mechanistrians.
The Prime Law One stated that any technology not made by the machines must be learnt from, then destroyed. (PROSE: Peril in Mechanistria)
Technology
The machines of Mechanistria provided for the Korads, creating tools, producing food and synthesising water. They used soarers to travel from place to place. Besides this, the Korads had little advanced technology. (PROSE: Peril in Mechanistria)
History
The Korad were the original race on the world of Korad. As machines became more advanced, a group broke off from the Korads and became the Mechanistrians. These Mechanistrians joined their brains to the machines, becoming immortal. The Korads were kept only as mechanics and in menial tasks on the renamed world of Mechanistria. Though revolts were attempted, they all failed, and the Korads were used as slaves for almost ten million years.
When the First Doctor came to Mechanstria, he was saved from a Grukker by the Korads and taken to one of their underground havens. When he told them of his TARDIS, Drako planned to use it to go back in time and destroy the machines before they took over. He saved the Doctor and then travelled back in time, saving his planet. (PROSE: Peril in Mechanistria)
Despite the change in the timeline, two Korads and a Mechanistrian were seen shopping at the Frenko Bazaar. (COMIC: Prisoners of Time)