Dalek Progenitor

The Progenitor device was a piece of Dalek technology designed to create new Daleks. It stored pure Dalek DNA, and when properly utilized and fueled, could both reproduce fully-grown Dalek mutants and functional battle armour. Thousands of such machines were created by the Dalek Empire. Eventually, all but one were lost. The last of these devices was used to restore the Dalek race by establishing the New Dalek Paradigm (TV: Victory of the Daleks)

History
During the Last Great Time War, the Daleks used them to quickly populate the areas of the universe they conquered. They planned to create a new paradigm of Daleks armed with Temporal Cannons that could erase their victims from history. But the new planned paradigm was never deployed, the Eternity Circle being stopped by the War Doctor and Borusa. (PROSE: Engines of War)

Immediately after the 21st century Dalek invasion was foiled by Donna Noble, the entire New Dalek Empire was almost completely destroyed by the human Meta-Crisis Tenth Doctor. (TV: Journey's End) However, a single Dalek saucer, badly damaged and severely depleted, escaped destruction. The three Dalek drones on board were the last free Daleks in existence. They detected the signal of the last Progenitor device, acquired it, and installed it in their saucer. They were unable to use it to create new Daleks, however, as the Progenitor did not recognize them: these three Daleks had been created from the cells of Davros (and did not have the requisite "pure" Dalek DNA). However, it had been programmed to recognise the Time Lord known as "the Doctor" as the enemy of all Daleks. If they could somehow acquire the Doctor's testimony that they were indeed Daleks, the progenitor would accept this as proof and would begin functioning.

To accomplish this, the three Daleks went back in time to World War II and created an android called Professor Edwin Bracewell in London. While one Dalek remained in Earth's orbit with the Progenitor, the other two feigned to be Bracewell's simple robots, called "Ironsides". They eventually tricked Winston Churchill into calling the Eleventh Doctor. After arriving, the Doctor became so confused and frustrated that, in a fit of anger, he struck an "Ironside" repeatedly, addressed them as "Daleks", and briefly recounted his violent history with them. The Daleks transmitted this testimony to the Progenitor, which recognised the Doctor, and duly accepted the command to activate. Shortly afterward, the first five individuals of the New Dalek Paradigm were created. The first action of the New Paradigm Daleks was to disintegrate their three "unclean" forebears, who willingly offered themselves for extermination. The New Paradigm then escaped with the Progenitor through a time corridor to the future and successfully created a new empire, while the Doctor and Amy Pond remained on Earth to defuse the Oblivion Continuum bomb inside the android Bracewell. (TV: Victory of the Daleks)

Behind the scenes

 * A cut line had the Doctor stating that the Daleks had been altering their DNA in order to keep surviving for a long time, indicating other, older incarnations of the Daleks wouldn't be recognised by the Progenitor either. This is also claimed by The Dalek Handbook.