Heruun was a planet in the Pegasus galaxy which has a Stargate. Five hundred years ago Fenris spaceship Aegis stopped a culling of Heruun.He was caught between the planet Heruun and a Wraith fleet who was preparing to culling its inhabitants, when his ship dropped out of hyperspace to make a course correction. Fenrir and his vastly superior ship managed to win the battle that followed, but took in injuries and crash-landed on Heruun's moon.
With no way to completely repair his ship without help, he kidnapped several times Heruun locals and temporarily brainwashed them to fix their ship for a period of weeks, then send them back home with their memories of where they've been and done in that time period erased.
In 2007, the planet was visited by the Atlantis expedition who discovered the Aegis and Fenrir. The expedition was able to get Fenrir to send everyone kidnapped back, but those kidnapped by Fenrir suffered a fatal infection from the nanites used by the Asgard crossing the blood-brain barrier and Doctor Jennifer Keller struggled to find a cure with no luck. The planet came under attack from a Wraith hive ship seeking the Asgard technology aboard Aegis with Wraith ground forces assaulting the population with the aid of Wraith worshippers amongst the population who saw the Wraith as their only hope for a cure. As the Aegis and the hive ship are destroyed by an isa device, the Heruuni are able to kill most of the Wraith and capture the rest. Keller is able to make a deal with the surviving Wraith where they use the Gift of Life to cure the ill Heruuni in exchange for being allowed to depart through the Stargate. After the end of the Wraith threat, the loss of the Aegis and the revelations that came from the arrival of the Atlantis expedition lead to a change in the Heruuni culture for the better. (SGA: "Nightfall")