Tyr is a member of the Asgard race and was a highly distinguished member of their military as well as served as commander of the Valkyries. He was involved in operations against the Goa'uld in the Milky Way galaxy and was present when the Protected Planets Treaty was struck. Following the creation of the Treaty, Tyr took a number of Humans under his protection and settled them on a world devoid of a Stargate called Vanaheim. The planet was in the grips of an ice age and many of the settlers died as a result of the cold winter but managed to prosper during the other climates. Tyr was known to have transported a Stargate from another world to Vanaheim and warned the Human inhabitants of the world of the threat of the Goa'uld. He also differed on the opinion of deploying Thor's Hammer on Vanaheim; instead, Tyr provided its inahbitants with Shock spears as well as allowed them to develop into an advanced people. This was because Tyr felt that the only way the Human inhabitants of Vanaheim could defend against the Goa'uld was by defending themselves.
His actions, however, proved to be quite unpopular amongst the Asgard who felt that Tyr had interferred in the natural development of a species. It was Thor who stripped Tyr of his rank and demoted him to being the commander of a single ship. Despite this being the case, the inhabitants of Vanaheim prospered and held Tyr in high esteem as a god. (RPG: "Fantastic Frontiers: Stargate Season One")