Dalek-Movellan War

The Dalek-Movellan War was a galactic war fought between the Cyborg Daleks and the android Movellans. The Dalek Empire and the Movellans were each expanding to control the galaxy (presumably the Mutter's Spiral) when they met and fought to destroy each other.

Historical overview
According to one account, Gordon Lowery recalled the conflict as one of the last instances of Dalek activity in human space before the year 4000, estimating that it took place approximately a thousand years before then, (PROSE: Mission to the Unknown) while the Matrix on Gallifrey recorded that Dalek and Movellan fleets were engaged in star system 4-X-Alpha-4 in 4949. (AUDIO: Neverland)

At some point during the war the Twelfth Doctor piloted the TARDIS there in order to sterilise the being that was following him, Nardole, and Bill Potts. Nardole succeeded in sealing the area the Daleks were in. (TV: The Pilot)

For centuries, the two were locked in a long stalemate, each side's purely logical battle computers keeping them in deadlock. Hundreds of Dalek and Movellan battlecruisers flew across space, without a single shot being fired. To resolve this, the Daleks returned to their homeworld of Skaro to search the ruins of the Kaled dome for their creator, Davros. They believed that his unpredictable biological mind would allow them to re-program their computers to make unanticipated manoeuvres against the Movellans. The Movellans followed the Daleks to Skaro and ultimately learned of their plan. The Fourth Doctor, landing by chance on Skaro, was captured by the Movellans for the same reason. He later defeated both the Movellans and the Daleks, as well as the resurrected Davros. Davros was taken by Tyssan, a rescued Dalek slave worker, to Earth for trial. (TV: Destiny of the Daleks)

After the trial, Davros was placed in a cryogenic freezer in a space station which served as his prison. The war continued for the next ninety or so years, until the Movellans developed a virus that could permeate the casing of Daleks and destroy them. There were so many Dalek casualties that Dalek troopers were recruited to fight for the Dalek Empire. The Supreme Dalek ordered Davros recovered from his prison so he could find a cure. During this time, the Daleks began using a different form of time travel — time corridors. They also used these to place duplicates to manipulate events for the Daleks' best interests. (TV: Resurrection of the Daleks)

Now revived and more filled with hatred than ever, Davros turned the Daleks on the space station against each other. Wide-scale hostilities between the factions led to the Imperial-Renegade Dalek Civil War. (TV: Resurrection of the Daleks, Revelation of the Daleks, Remembrance of the Daleks)

Possible non-existence
The Dalek Prime claimed it had contrived a hoax of a war with the Movellans (whom the Daleks had created for the specific purpose of having an "enemy") as well as the Imperial-Renegade civil war as part of a plan to save Skaro from the Hand of Omega. (PROSE: War of the Daleks)