Age of Universal Peace
The Age of Universal Peace started at the beginning of the year 2409. It came following the Dalek invasion of Earth's solar system in 2400. (PROSE: Break-through!)
Historical discrepancies with the Dalek Wars
Accounts of the Age of Universal Peace lasting "two hundred years" until the beginning of the invasion of the 27th century, (COMIC: The Mechanical Planet) conflicted with accounts of the Dalek Wars, specifically the Second Dalek War which was fought throughout much of the 26th century. (TV: Frontier in Space, PROSE: Love and War, Prisoner of the Daleks, et al.)
The narrator of The Dalek Conquests noted that writing a precise chronological account of Dalek history was made very difficult by the fact that the Daleks possessed time travel. The exact details of the effects this may have had on Dalek history and the aftermath of the 25th century invasion in particular is unclear. (AUDIO: The Dalek Conquests)
Indeed, it was known that Daleks with time travel native to the 40th century attempted to go back in time to launch an invasion of Earth in 2415 but the Golden Emperor's time machine was faulty and he ended up in 1415 during the Battle of Agincourt. Without their leader the invasion was a failure and the remaining Daleks quickly surrendered. (COMIC: The Secret of the Emperor)