The Slough of the Disunited Planets was a location where the Warkeeper lived. The Warkeeper was protected from a horde of enemy creatures by the Hawk troops. According to one of the Harpies, it was approximately fifty billion miles away from Earth through hyperspace.
According to the Tenth Doctor, the Disunited Planets "never stopped scrapping, made a radioactive hell of an entire galaxy" and that "any sane space traveller avoids this area like the plague". He believed the purpose was to use clone armies to research and develop new strategies and weapons, which the Warkeeper could then sell to others. (COMIC: The Warkeeper's Crown)