Yep, I'll bet a Viking picked it up in a raid and then tossed it away after checking it over for any gold or encrusted jewels. He had no idea the contents were far more valuable than any jewels or precious metals.
The careless tossing reminds me of the Talmud story of the "Gentile Prince and the Mezuzah."
(The prince didn't know the value of what he had received and was careless with it.)
There is no reason to suspect Viking involvement, other than the fact that it was dropped somewhere where it shouldn't have been. Fumbles and the Vikings go hand in hand, but that is not enough to prove guilt here! Where's my lawywer!
What's in YOUR wallet?