@wojo I immediately thought he was adapting the Scandinavian word "vång", which means field, and is present in many place names. Looking at the etymology entry for that, I see it's actually cognate with an Old English word "wang" that means "paradise". I would not be surprised if Tolkien was aware of both historical meanings.
The entry in SAOB (the Swedish equivalent of the OED): https://www.saob.se/artikel/?seek=V%C3%A5ng&pz=1
@bkhl nor would I! Thanks for the info.
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