Daleks' timeline

By several accounts, the Dalek species had a unique timeline which was heavily interfered with on multiple occasions from conflicting accounts of their origins to being further complicated by the Last Great Time War. (TV: Genesis of the Daleks, PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe, Dalek Combat Training Manual)

The Eighth Doctor found Dalek history a difficult thing to remember because it was always changing. (PROSE: Alien Bodies) A member of Faction Paradox thought that this was because the Doctor "tricked the Dalek Empire into tangling their timeline so bad that their history collapsed under the weight of the paradoxes". (PROSE: Unnatural History) Historians who studied the Daleks noted the Daleks themselves often dipped back into their own past in their attempts to rewrite past failures, (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe) and not even the Time Lords could organise all accounts of Dalek history together. (PROSE: Dalek Combat Training Manual) The Tenth Doctor reflected that "Dalek history was confusing enough before the Time War." (PROSE: Prisoner of the Daleks)

During the Time War, the Time Lords scrutinised Dalek history with the assistance of the Doctor's memories, the results of which were recorded in the Dalek Combat Training Manual. To that end, they ordered notable incidents into timelines of both Dalek history and of Dalek activity in the linear history of the universe. Furthering their knowledge, the Time Lords used the Matrix to project encounters, then thought to be theoretical, between the Doctor and the Daleks in the post-Time War universe. In addition to the "ratified accounts", there was also a vast amount of additional information gathered from a variety of sources, the validity of which was disputed by scholars as some accounts contradicted what was known about the Daleks from "more authoritative sources". It was a matter of opinion whether these were apocryphal or evidence of Dalek activity in parallel dimensions. Such "anomalies" in Dalek history included alternative accounts of the Thal-Dalek battle, a "very different origin story" for the Daleks and their Emperor which contradicted the known record of Davros, the Space Security Service's conflict with the Daleks, an account from the planet Strellin, the Dalek Time Controller and Dalek Time Strategist, the activity of the Dalek Time Squad. (PROSE: Dalek Combat Training Manual)