P3X-775 appears to be an uninhabited planet covered by rain forest, with no signs of radio traffic or traces of pollution that would suggest civilization. It is, however, under the jurisdiction of the Taldor, the judicial body of an advanced race of beings which appeared to SG-1 only as disembodied voices. It was on P3X-775 that SG-1 encountered Roshure, and they were sentenced by the Taldor to life in prison on Hadante for aiding a criminal.
Cross Reference: Hadante, Roshure, Taldor
Episode Reference: Prisoners