Skarosian

Qualen, a Gallifreyan historian, claimed that a single humanoid race, the Skarosians. had lived on Skaro before they diverged into the Thals and the Kaleds. Eventually, the two races came into contact and engaged in a Thousand Year War which saw the Kaleds mutate into the Daleks. (PROSE: The Dalek Problem) Human historians in the post-Time War universe were aware of accounts which told that the humanoid species of Skaro were the descendants of proto-humans who had been transplanted onto the planet by alien powers. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe)

The human historians were also aware of postulations that there might, at one time, have existed a third intelligent species on Skaro, the Dals. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe) On Skaro, the Dals were known to have gone extinct by the time of the war between the Thals and the Kaleds, along with the Tharons, as a result of a programme of genocide orchestrated by the Kaled government. (AUDIO: Purity)