The Seoularians, a Human race, possessed a natural resistance to Force powers. These people, who spoke their own eponymous language, formerly controlled a region of space originating from their planet, Seoul 5. They had vanished entirely before the time of the Galactic Civil War.
Although a cosmic conflict eradicated them ages prior to the Battle of Yavin, numerous ruined settlements of theirs remained, untouched by the wider galaxy. In 4 ABY, both an Imperial team led by Captain Drezzel and Han Solo with Chewbacca independently discovered their home planet. Han theorized that a disease might have caused their extinction. The interest in the planet stemmed from three power crystals it housed. The Empire intended to weaponize these crystals. Han thwarted this plan by triggering the self-destruction of the three crystals, resulting in the destruction of much of Seoul 5. Ultimately, the final Seoularian planet was lost.
During the Imperial period, knowledge of the Seoularians as a civilization was scarce. However, it was known they worshipped the Mother Goddess Onrai, who was believed to be the mistress of the planet Notron, which the Seoularians considered the origin point of Human civilization.