[Deaf Smith]

No mention in the excerpt that the Vikings may have procured the beaver pelts from Greenland during their travels/settlements.

The beaver pelts would have been rare if only the Vikings had them.

Unless the Vikings raided Eurasia to get the pelts.

[SunkenCiv]

Beavers (and Vikings) are also native to northern Eurasia, so they may have just trapped ‘em themselves, or traded with neighbors.