Dorthonion was a highland region to the north of Beleriand, where Treebeard had travelled in earlier days (this must have been at least some 6,500 years before the War of the Ring, because Dorthonion was destroyed - or at least cut off by the Sea - at the end of the First Age). The land was famed for its pine trees, and indeed Dorthonion means 'Land of Pines'. The name Orod-na-Thôn carries on this theme - it means 'Pine-mountain', and it lay within the borders of Dorthonion, though its exact location is nowhere recorded.

Some sources give an alternative interpretation, suggesting that Orod-na-Thôn is simply another name for Dorthonion itself. This is a natural assumption based on the text of Treebeard's song, but in his unfinished detailed index to The Lord of the Rings, Tolkien is clear that the name refers to an individual mountain, rather than the entire land.