What could this movie be? (its an animated movie from when i was a small kid, im 18 atm)

Okay so this movie is from when i was pretty small kid, (im 18 now) so bear with me if the details aren’t perfect. This is an animated film, and it starts off i think showing these dark vikings that are basically spreading out everywhere burning and looting all villages of all their gold. It then shows a village and the main character is some boy. There is a very special book with a cover inscribed with gold on it. There is also a girl who lives in the woods and he sneaks out to go meet with her a bunch before the vikings arrive. He helps her resolve some curse she had i think she was a spirit or something trapped to the woods. At the end of the movie the book that had a cover of gold is still there however the gold has been stripped probably due to the vikings. It was just a normal looking cover.