Stargate - Alpha One

The Asgard, a powerful race of extra-terrestrials, has visited Earth many times in its history. Most notably, they gave wisdom to the Norse peoples and transplanted their culture to another world, where they would be safe from the Goa’uld.

In the reality that the Alpha Team comes from, the Asgard had a treaty with the Goa’uld, protecting those planets from further interference (from either race). The only mention of them as yet in their new universe was the rumor that they were terrorizing the people of Coalhearth – a rumor which proved false.