PX3-595 is an Asgard protected planet. The natives, known as Tiernods, are primitive, and hide from predators in caves, using a small palm-sized Asgard device to vanish. The mission of the rogue NID off-world team was to steal an Asgard cloaking device from the planet and secretly return it to Earth for study.
Cross Reference: Asgard, Invisibility, NID Off-World Operation
Episode Reference: Shades of Grey