- The oldest form of starlight is this old. In the year 2001, Dana Scully and Fox Mulder would often discuss the fact that they would look up at billion year old starlight. (TXF: "This is Not Happening")
A rock blasts off the face of Mars by a meteor impact. It ends in Earth's atmosphere and lands in what will be Siberia. It contains dormant biological organisms capable of entering living bodies. (TXF: "Terma")
- Over 350 million years ago
- In Earth's Surilian period, cockroaches are believed to have originated. (TXF: "War of the Coprophages")
- 100 million years ago
- The remains of various dinosaurs begin the process of transforming into crude oil. (TLG: "Like Water for Octane"):: A meteor crashes into north Alaska. This meteor contained an alien worm that thrived on ammonia, that would survive for 250,000 years. (TXF: "Ice")::: In 2000, Shelly Mizer jokingly claimed to have played music with Jason Guthrie during this time. (TLG: "Like Water for Octane"):: "A quarter of a million years ago."
- While following strange tracks through the snow of North Texas, two cavemen are attacked by an alien. One of the primitives is killed by the creature, while the other dies of exposure to the alien's toxic blood. The bones of the primitive men will later be discovered in 1998. (The X-Files Movie)::: Ancient Egyptian history begins around 3000 BC, with the earliest evidence of agriculture around 10,000 BC. This would still be during the Pleistocene epoch, and is the time when the Hall of Bulls cave art was painted in France. Amen-Re was first worshipped in 2400 BC. The actual Great Seal was (believed to be) invented in 1776.
- 6th century BC
- Pythagoras discovers the power of numbers and comes up with the field of numerology. (TXF: "Improbable")
- 10th century
- A ceremonial axe is created to cleave open skulls of those who do not follow Christianity. (TXF: "Via Negativa")
- "Over a thousand years" before 2000.
The Anasazi culture disappears in the Southwest. Some of their elders hide in one particular pueblo that contains magnetite, protecting them from the aliens. The Cigarette Smoking Man thinks of these elders as "the first shadow government." (TXF: "The Truth")