Eaters of the Dead by Michael Crichton. This is the book that "The 13th Warrior" was based on. It follows the POV of an arab prisoner aboard a viking vessel. It's been a long time since I've read it or seen the movie.
I'd also second anything by Cromwell. He's regarded as one of the best of the best.
Also, you can check out out the "Terra Incognata" series (The Edge of the World) by Kevin J Anderson. It's more epic fantasy than historical fiction. But, its mainly based on norse mythology and viking culture.
There's also "The Last Light of the Sun" by Guy Gavriel Key, it's an alternate history and I think it's part of a series.
Other ones that I've seen mentioned but am not familiar with include:
"The Thrall's Tale" by Judith Lindbergh
"Raven's Wind" by Victor Canning
"The Sea Road" by Margaret Elphinstone
Also found this
link that may be of help to you.
Best of luck! Keep us updated with whatever you decide
