The Oppressors were an ancient race that once ruled over most of the Oralian sector long ago beyond many of the historical records from the species in the region. (Star Trek: Pioneer) The exact location of the Oppressors’ homeworld was unknown, all who have searched for it have never succeeded. In 2383, the crew of the USS Pioneer discovered an Oppressor Gateway on the once mythical planet of Yoth. ("The Forgotten Planet")