O reino de Thranduil na Floresta das Trevas do Norte é conhecido como Reino da Floresta , ou mais comumente, o reino de Thranduil .
In the North also there had been war and evil. The realm of Thranduil was invaded, and there was long battle under the trees and great ruin of fire; [...].
The Lord of the Rings: Return of the King - Appendix B: The Tale of Years
Thranduil, king in the north of Greenwood the Great, was one of these. [...] Thus in one essay Thranduil's realm is said to have extended into the woods surrounding the Lonely Mountain and growing along the shores of the Long Lake, [...].
Unfinished Tales: Chapter III - The History of Galadriel and Celeborn: Appendix B - The Sindarin Princes of the Silvan Elves
So it was that Sauron prepared two strokes- in which many saw the beginnings of the War of the Ring. They were made together. The Orcs assailed the realm of Thranduil, with orders to recapture Gollum; [...].
Unfinished Tales: Chapter IV - The Hunt for the Ring: Of the Journey of the Black Riders according to the account that Gandalf gave to Frodo
Seu capital é chamado de 'Elvenking's Halls', também conhecido como 'Halls of Thranduil'. Este reino não adotou nenhum nome de dialeto Sindarin, já que os Elfos Silvestres não falavam Sindarin, apesar de alguns de seus ancestrais serem de origem Sindarin.