I'm sorry if this has been asked before. I've been binge watching Vikings, and I can't help but wonder how much of the traditions and cultural values are real and what's just for dramatic effect. I know Ragnar Lothbrook existed, but how much of his story is correct? Did his brother really marry into a Francish family? What about his sons? Are they portrayed accurately? The rituals and spirituality?

Any historical information about the things they show in Vikings would be really helpful! Thank you!

(I would just Google it but it's more fun to get an answer from someone who is passionate about the subject and I think it gives someone a good chance to show what they studied so hard for.)