The Axis

The Axis was the hub of a spindle of dead-end timelines where history had spiralled off due to catastrophic decisions being made. They were cut off from the rest of reality.

Such changes occurred often due to meddling by the Time Lords or by the immortal, omnipotent Overseer of the Axis, who had little love for their kind. Inside the Axis was the Oracle room, where a set of locked doors represented the dead end timelines being locked away. It became infected when a mad inhabitant of one of the timelines entered the Axis. (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)