Outer Galaxies War

Human historians in the post-Time War universe understood that the Daleks, following the Dalek Wars focused on Mutter's Spiral and the Dalek-Mechanoid War, fought a war across the Outer Galaxies.

History
In the half a millennium leading up to the year 4000, the Daleks, having fallen back from their ambitions to conquer Mutter's Spiral following the conflict with the Combined Galactic Resistance and the war with the Mechanoids, advanced towards the Outer Galaxies for new conquests. Whilst the limited observation technology of the Earth Empire observed the Dalek conquests of 70 planets in the Ninth Galactic System and 40 more in the constellation of Miros, both millions of light-years from their galaxy, later historians understood that these conquests were a mere fraction of extra-galactic Dalek gains, having conquered the Second, Third and Ninth Galaxy. The Anti-Dalek Force reported that the Daleks were suspected to be signing non-aggression pacts with other powers in the "outer planets".

The "great powers" of the Outer Galaxies included the Fifth Galaxy and the Tenth Galaxy, which was the largest of the group, the planets Gearon, Sentreal, and Malpha, and the planets of the Beaus, Warrien, and Planktus, who attended the Intergalactic Conference of Andromeda. Also represented was the Celation Nebula, (TV: The Daleks' Master Plan) which drifted along the Mutter's Spiral. (AUDIO: The Perfect Prisoners)

With Dalek gains in the Outer Galaxies consolidated by the dawn of the 40th century, the Dalek Supreme began the Daleks' master plan, which would take a century to complete. They aided Zephon in the overthrow of the Entity Gris in 3932 to assume control of the Fifth Galaxy. The now Master of the Fifth Galaxy in turn secured the allegiance of Celation and the Master of Beaus. Ultimately, representatives of all of the outer galaxies not under Dalek control were brought into the Daleks’ alliance: Gearon, Malpha, even Trantis came to join them. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe)

In 4000, the great powers of the Outer Galaxies, along with Mavic Chen, the Guardian of the Solar System, formed the Great Alliance with the Daleks in an attempt to invade the galaxy and obliterate Earth with the Time Destructor. The Daleks' treachery was revealed, and the surviving members of the Outer Galaxies fled to warn their planets and join forces, (TV: The Daleks' Master Plan) which lead into the Great War against the Daleks. (PROSE: The Evil of the Daleks)