Interesting short video about the possible origin of the crucible steel used to make the famous Viking Ulfberht swords.
There is no archaeological evidence that the Norse during the Viking Age had the technology or know-how to produce the steel used for the Ulfberht swords. It would be centuries after the Viking Age before Western Europe had the skills to produce steel as good. So, where did the steel come from during the Viking Age?
Hypothesis for origin of crucible steel
Historians are now zeroing in on the most likely origin being the Middle East. The Norse could have obtained the steel via the trade routes along the Russian river systems. If the hypothesis is correct, then it would have been a very strong incentive indeed for the dangerous Viking trade expeditions.
A Viking wielding an Ulfberht sword had a technological arms advantage.