Ten thousand years ago, with their race's growing genetic degradation problem, a rogue faction of the Asgard known as the Vanir decided to travel to the Pegasus galaxy and experiment on the human populations there in hopes of finding a cure. The Vanir took advantage of the war between the Ancients and the Wraith to work without interference and eventually managed to find something that enabled them to slow the degradation, but not cure it. However, the Vanir were counting upon the Ancients to win the war, but they lost and the Wraith turned their attention to the Vanir and other advanced races that could pose a threat to them. (SGA: "The Lost Tribe")