Ten Systems
From Tardis Wiki, the free Doctor Who reference
The Ten Systems were ten star systems associated with the Earth Alliance. This included Heron's World on the edge of the ten systems, Kalsos, (AUDIO: The Death of Hope) and the planet Ridius IV in the seventh system, said to be "a hundred colonies" away from Earth. (AUDIO: The Seeds of War)
Galactic Heritage was able to track the Decayed Master to the Ten Systems, where he took over the Death-Match. (AUDIO: Death Match)
The Eminence War spanned across the Ten Systems. (AUDIO: Rule of the Eminence)