5000

5000 was, according to the Fourth Doctor, the year of the Great Breakout, a time when humanity surged across the galaxy like a tidal wave. A ship en route to Titan Base encountered a virus of unknown origin. The Doctor identified it as a sentient virus known as the Swarm. After the Doctor was infected by the Swarm, he and Leela went to the Bi-Al Foundation, where they were helped by Professor Frederick Marius and K9 Mark I to defeat/cure the virus. When they returned to the TARDIS to depart, the professor gave them K9. This began the Doctor's long association with the K9 series of robots. (TV: The Invisible Enemy) In response to Rose Tyler's comment that a succeeding K9 model looked "disco", the Tenth Doctor asserted that "in the year 5000 this was cutting edge." (TV: School Reunion)

The Eighth Doctor and his companions Fitz Kreiner and Trix MacMillan visited Moscow in this year. By this time, Earth was undergoing another Ice Age (PROSE: Emotional Chemistry) and experienced World War VI, fought against the Supreme Alliance of Eastern States led by the tyrannical Magnus Greel. (TV: The Talons of Weng-Chiang; PROSE: Doctor Who and the Talons of Weng-Chiang; AUDIO: The Butcher of Brisbane)

The Great War, fought against the Daleks since the year 4000, entered its thousandth year. By this time the conflict was inching ever closer towards its conclusion. (PROSE: The Evil of the Daleks)

K9 once gave the date that Marius gave him to the Doctor as "one-one-one-five-zero-zero-zero". Y5K compliance was an issue in this year. It prevented Professor Marius from taking K9 Mark I to Earth. (PROSE: The Gallifrey Chronicles)

The Third Doctor visited London. (COMIC: A Stitch in Time)