It seems that the Neuri are sorcerers, if one is to believe the Scythians and the Greeks established in Scythia; for each Neurian changes himself, once in the year, into the form of a wolf, and he continues in that form for several days, after which he resumes his former shape.
–Histories, Book IV, chapter 105
According to Herodotus, the Neuri was a Scythian tribe living on the farthest reaches of their boundaries, along the Dnieper River – roughly modern-day Poland – who were fearsome warriors, reliable magic-users, and regular shapeshifters who favored the shape of wolves, bears and birds. If the Scythians can be said to have been the Vanir of Germanic Lore – as is often considered among some scholars – then this reference could indicate the origin of Old European wolf lore. Finally, this verse from Hyndluljóð 32, though not directly related to werewolves, is interesting nonetheless:
Eru valur allar fra Vidolfui,
Those wise-woman all from Far-Roaming Wolf,
Wise-men all from Choosers of the Longbeam,
Bearers of Seiðr from Black-Beheaded,
Jötuns all from First-Shrieker come.
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Hyndlalied translation by Valarie Wright, from Old Europe’s Seið-Bearers: Their Mythic Origins and Lineage, 2010