The Axis

The Axis was a hub of a spindle of dead-end timelines where history had spiralled off due to catastrophic directions being made. This resulted in them being cut off from the rest of reality.

Typically, such changes occurred due to the result of meddling by the Time Lords or by the immortal, omnipotent Overseer of the Axis who had little love for their kind. Inside the Axis resided the Oracle room where a set of locked doors were present and represented the dead end timelines being locked away. It became infected when a mad inhabitant of one of the timelines entered the Axis itself. (BFA: The Axis of Insanity)

Romana, Leela, Narvin and Irving Braxiatel travelled to the Axis to find a Gallifrey that had a future for them. (BFG: Reborn)