When The Historian was created, he was a lizard-like creature who had a 'sister' called Navilia.
When The Historian got older, he was given the option to stay on Eideria or explore the universe, unfortunately during this time, The lizard-like creatures Eiderians were born as were viewed as Messengers of Death due to an ancient war, so The Historian had to shape shift into a form which was shown as suitable, this form being Human, once the form was chosen, he was placed inside an orb where he started The Regrowth Cycle, otherwise known as 'Regeneration.' After exiting the orb, he was granted a ship known as 'The ETTM' standing for 'Eiderian Time Travel Manipulation' He left Eideria, but The ETTM somehow had a malfunction and The Historian crashed on Earth.
In his first incarnation, The Historian was a grandfatherly figure who had a fondness for Jaffa Cakes, often stating "Enlighten a jaffa cake?" with a warm smile, While The Historian was travelling, he met his 'sister' His sister claimed to be holding in regrowth energy after being exposed to radiation poisoning on Metebelis III, She had to be placed inside one of The Historian's spare orbs before it began, after it was complete she was teleported to her ETTM, The ETTM crashed to Earth as it used up most of it's energy to ensure no damage was done to The Historian nor The ETTM in particular, The Ship landed near an office, this was where he met The Thinker.
Soon in his life, The ETTM was recalled back to Eideria for The Elimination of Eideria, The Historian had no choice but to fight he had to use an advanced demat gun to destroy both Cybermen and The Eiderians, this caused him to regenerate.