- You may be looking for Dark Times.
The distant past was that period which was historically remote to the Doctor's usual travels. It had no exact date range, but could be considered to extend from the Big Bang (and perhaps earlier) to the development of modern humans, in about 100,000 BC. The Dark Times of the universe were known to have occurred in the distant past.
Beginning of the universe
At the beginning of time, the Big Bang occurred due to a combination of at least two events: an ejection of fuel from the leper ship Terminus (TV: Terminus) and the explosion of the time ship Vipod Mor. (AUDIO: Slipback) According to the Seventh Doctor, the creation of the universe occurred 13,500,020,012 years prior to 2109 when he decided to celebrate it. (PROSE: Transit) The TARDIS attempted to return to this point in time, which was also known as Event One, only to be prevented from doing so. (TV: Castrovalva) The first stars and planets were formed in the aftermath of the explosion. Life evolved and civilisations arose on many worlds. (PROSE: Timewyrm: Apocalypse, Falls the Shadow)
Virus 7001B, one of millions of viruses released from the Amethyst Viral Containment Station in the far future, was sent back to time to the beginning of the universe and resulted in the creation of life itself. (AUDIO: The Viyran Solution)
The Grey Man's race observed as the first humanoid race destroyed themselves in bacteriological warfare. In response, the Grey Man created Cathedral to introduce uncertainty to the concept of duality which his people had imposed on the universe. (PROSE: Falls the Shadow)
Billions of years BC
According to one account, the year 10,000,000,000 BC was at the "dawn of human civili[s]ation". During this time, the Eleventh Doctor accidentally started a galactic space-war that changed the course of human history every time something blew up. This caused radical changes in the 21st century, such as humans changing species before the timeline was set right again. (COMIC: Short-Change)
According to another account, the Earth formed in the solar system around 6,000,000,000 BC. The Eleventh Doctor photographed what would be the site of the Caliburn House as part of his investigation of the Caliburn Ghost. (TV: Hide) However, the Tenth Doctor claimed he went back "4.6 billion years" from 2007 at a point to when there was "no solar system. Not yet." The Doctor and Donna Noble saw the Secret Heart, a Racnoss spaceship hiding from a war and entering what would become the solar system as the Earth began forming around it. (TV: The Runaway Bride) At the same time, the Sentience was trapped inside the forming Earth, underneath the area that would later be known as Crook Marsham. (PROSE: Nightshade) According to one account, the Moon left the Cthalctose homeworld around 6,000,000,000 BC and eventually entered the solar system. (PROSE: Eternity Weeps)
Around 5,000,000,000 BC, the Arkive were created to preserve the knowledge of their creators after the creators' planet was destroyed by a supernova. The plan failed and the Arkive was badly damaged by the supernova. Eventually, it drifted into the solar system and became the core of Mnemosyne. (PROSE: The Wheel of Ice)
Hundreds of millions of years BC
Around 1,000,000,000 to 500,000,000 BC, the Angels created the bases on Belial and Moloch. They then used the "Mushroom Farm" (which could modify morphic fields) to change their shape. (PROSE: Lucifer Rising)
- A more precise date can't be given, since this was gleaned from archaeological research and the living Angels refused to communicate with the humans.
According to one account, life developed on the Earth around 450,000,000 BC when the Archaeons seeded it and carefully controlled life from their vivariums. This account claimed that the Moon was already orbiting the Earth. There, the Archaeons were carefully nurturing the early forms of life before they disappeared when they were trapped inside a stasis field. (AUDIO: The Beginning) According to another account, the last Jagaroth ship exploded on primitive Earth around 400,000,000 BC. The explosion killed the crew and splintered Scaroth into 12 sections in human history. The explosion also caused the development of life on Earth, meaning that to prevent the explosion would have left the planet a desolate rock. (TV: City of Death)
Around 150,000,000 BC, the Millennium War occurred, causing massive amounts of death and carnage. (PROSE: The Quantum Archangel) Also around this time, a civil war erupted on Kastria, which led to the destruction of Eldrad and the eventual extinction of the Kastrians. (TV: The Hand of Fear) A planet inhabited by parasitic lifeforms was destroyed by its dying star. One individual was able to escape, but crashed on Earth in the Mariana Trench. (AUDIO: Submission)
Tens of millions of years BC
The Seventh Doctor dropped off Ace on Earth during the Cretaceous period. (COMIC: Train-Flight) After arriving to pick her up around 75 million years BC, he witnessed her lead the dinosaurs in destroying an alien colony being constructed by slave labour. (PROSE: Living in the Past)
65 million years BC, the crash of a human freighter from the future caused the extinction of the dinosaurs. (TV: Earthshock) In the immediate aftermath of the event, Jack Harkness, who was present on Earth, lived off of dinosaur meat. (TV: Fragments) Adric, who was on board the freighter, survived and used the alien computer on the ship to create a city of intelligent scorpions, which he ruled over for five hundred years until he was reunited with the Fifth Doctor and Nyssa. (AUDIO: The Boy That Time Forgot)
The Cardiff Space-Time Rift connected the Palaeocene ocean and the Cardiff Bay in 2008. The amino-acids from the Palaeocene broke down pollutants like oil, improving the quality of sea-water. (PROSE: The Undertaker's Gift)
Around 50 million BC, Arkive tried to attract the Silurians to rescue itself. The attempt failed and the rings of Saturn were created by the destruction of Mnemosyne. (PROSE: The Wheel of Ice) Also around this time, the Eighth Doctor and Bernice Summerfield were briefly transported into Epsilon Minima's past. (AUDIO: Benny's Story)
Around 15 million BC, a number of stones were carved with organic-looking reliefs that seemed to move when viewed. The Seventh Doctor found some of them in a museum in 1915 Haiti. (PROSE: White Darkness)