In Star Trek, time-travel is very common. But I’m only interested in travel to Earth’s past when it also hosted humans (Q transporting Picard to Earth when life was originating won’t be counted). Some examples that come to mind:
- In Star Trek: The First Contact, Borg queen and Picard went back to 2063 Earth to prevent and protect the first contact respectively.
- In Star Trek IV: A Voyage Home, Kirk and crew transported back to 1986 to bring humpback whales.
- In an episode of Star Trek: The Original Series, Kirk and crew got accidentally transported back to 1960’s (not exactly in my mind) while escaping a black hole.
- In an episode of Star Trek: The Original Series, Kirk and crew went back to 1930’s (not exactly in mind) using Guardian of Forever.
What's the earliest point in human civilisation that anyone has time-travelled back to, in Star Trek?