Dorwinion or Dor-Winion, the "Land of Wines", is a land which lay on the northwestern shores of the Sea of Rhûn. In Dorwinion was made a heady wine, which was strong enough to let even Elves get drunk and fall asleep.
Nothing is known about the realm or its inhabitants, were they Elves or Men. Dorwinion may have been the only Avari realm close to the Westlands of Middle-earth. It was already well established while the Atanatári were still young.
Dorvinion is mentioned by in the Narn i Chîn Húrin, where it was drunk in Thingol's halls of Menegroth. It is said there to lie in the "Burning south", which might suggest it was a different "Dorwinion", or may just have referred to the fact it came from the more southern lands of Rhovanion by way of the Dwarf-road of Beleriand.
Tolkien in several unpublished text mentions Dorwinion mainly to the South. The canonical location was decided at random by Pauline Baynes while drawing her map of Middle-earth. Tolkien was surprised but agreed.}}
Certainly the element -Winion, apparently meaning "wine", has no probable origin in any known etymology pointing to an obscure (like Avarin) origin.