map of Earth, changes in tectonics of Earth show differences.

Located on the Ringworld, it is a one to one scale replica of the surface of the Sol System planet Earth, as it was several million years before the time of the stories.[1] Once inhabited by Homo-Habilis or Pak, precursor to Humanity it was conquered by Kzin of the Ringworld and occupied by a Kzinti force led by Chmeee.[2]

  1. Ringworld Engineers (novel)
  2. Ringworld's Children (novel)