Calfadoria was an inhabited planet. The Doctor had at one point met representatives of the Tri-Planet Alliance of Calfadoria. (PROSE: Business Unusual)
The people of Calfadoria illegally sent bio-engineered assassins to kill Sancroff, as they found his continued existence to be morally abhorrent. To preserve their alliances with other worlds, they programmed the assassins to kill all witnesses as well. (AUDIO: The Sirens of Time)
Behind the scenes
Calfadoria originally appeared in one of the unlicensed Audio Visuals.