Long before Christianity, the people of Northern Europe shared pantheons of Gods, the Aesir and the Vanir. The two pantheons together are referred to the Asgard. You might be confused at this point, if your only knowledge of the Asgard is from the TV show Stargate SG-1. The writers of the Stargate franchise seemed to be mythology fans, as they took many stories and rewrote them for their show. They also used Egyptian, Greek, Roman and Celtic stories.
The Asgard I'm referring to is the source material. The Gods and Goddesses worshiped by the people of what is now Denmark, Sweden, Norway, Finland, Germany and Poland. Though they believe that anyone can be a member of their religion if they choose.
This religion, more than any other, gets a lot of bad press. People like Hitler took these beliefs and made a mockery of them. He took symbols and remade them into things of evil and racism. This religion is not racist by any means. The symbols it uses are not racist. Though there are still people that try to make it so.
Asatru survived mostly in thanks to people who settled in isolated areas like Iceland. While some of the people who lived on the continent converted willingly, many were converted at the point of a sword. However, places like Iceland were difficult to get to and their priests were content to allow the stories of the Gods of their ancestors to be passed down through the generations as folklore until it was reestablished as a religion in the last hundred years.
