4000

In the year 4000, the Daleks held a meeting with representatives from seven outer galaxies to plot the invasion and overthrow of human-occupied space. (TV: Mission to the Unknown)

Six months later, the First Doctor became involved with the Space Security Service's investigation into the Daleks, Mavic Chen and the Time Destructor. This culminated in the destruction of Kembel. (TV: The Daleks' Master Plan) The Great War began in the wake of this event. (PROSE: The Evil of the Daleks)

After the death of Mavic Chen, a dynasty of his descendants slowly transformed the relatively democratic Galactic Federation into a new incarnation of the old Earth Empire, which had fallen approximately nine hundred years earlier. (PROSE: The Crystal Bucephalus)
 * Most likely, this new empire would become the Second Great and Bountiful Human Empire known to exist by the 42nd century.