Daleks are the natives of the planet Skaro, who turned themselves into mutants and put into tanks in order to fight for universal domination.
The Daleks, in order to compete with the Time Lord's Starbane, tried to make their own planet fly through time and space. Believing the First Beginner's TARDIS was the Doctor's TARDIS, they shot it down to bring it to them. The Beginner escaped but the TARDIS was harvested of its power and Skaro flew to the Starbane. The Beginner, knowing both sides played a bad part in the War drained Skaro of its ability to fly and locked the Starbane away forever. (Skaro)
The Second Beginner and Jo landed in a Dalek ship and was taken by a Dalek to the Dalek Emperor who said that he'll be taken to the Grand Master. However they ran, but found the TARDIS being held in a forcefield. Jo pushed a Dalek into some controls which hit wiring that disabled the forcefield, allowing for their getaway.
The Writer and Spike Dimentos blackmailed the Daleks into fighting for them in an attempt to raise an army against the Death and the Cybermen. They were victorious and returned back to where they came from. (Battle of the Beginner)