Halldon

The Halldons were a race of powerful beings.

On Ollendorf 2, the Doctor discovered the unpublished writings of a human scientist, Bryant Anderson, next to Anderson's own corpse and the remains of a Dalek. The papers revealed that shortly before his death, Anderson had discovered the true origin of the Daleks. In ancient times, the Halldons, as part of a scientific experiment, had transplanted Earth humans to the barren planet Ameron and artifically accelerated their evolution. Within two hundred years, the Halldons' test subjects had advanced to such an extent as to build fearsome weapons which frightened even their Halldon masters.

Realizing the experiment was spinning out of control, the Halldons attempted to wipe out the Ameron humans, only for them to defend themselves and retaliate to the point of completely exterminating the Halldons. Free to advance unhindered, the evolved humans, determined to ensure their own survival, continued to evolve and eventually became the Daleks whom the Earth humans feared so greatly. (PROSE: We are the Daleks!)

Behind the scenes
According to the Doctor Who Annual 2006, the Halldons once engaged in a time war with the Eternals, which the Time Lords put a stop to. Doctor Who: Monsters and Villains claims that the Halldons were the ancestors of the Brothers of Hame, who created the Forest of Cheem.