| Category | Valleys |
| Continent | Brucrumus |
| Region | Grashakh |
| Map | Thingrorn |
The Vale of Thaena is a markedly rugged valley nestled within the Inghild Peaks. Bearing the scars of deep fissures and gorges, it conceals an incongruous evergreen tropical forest. Wisps of steam perpetually drift upward from hidden sources, a cooling mechanism surrounding a demon giant imprisoned beneath the valley floor.
In the Demon Spawn War (89 GE - 269 GE), a son was born to Surtur and a cunning demoness; a succubus named Ezryn in service to Rilthang. Charmed during the copulation, Surtur wanted nothing to do with a son tainted by demon blood. Named Thaena by his mother, their son's outbursts of anger and rage resulted in him becoming increasingly hotter. Reports from the time indicate that his fury generated such intense heat that even fiery beings like Surtur and Kossuth could feel it. While warm to them, it was brutally scorching to others; some say that in fits of rage, Thaena was akin to a miniature star, scorching the land and siphoning moisture from the surrounding area. Deemed a threat to both sides, in one of the rare moments of cooperation, the Covenant and the demon lord Ogtha paused their war until the matter of Thaena's rampages could be resolved. Willing to sacrifice an army to lure their target into a trap, Ogtha sent two demon divisions into what would become known as the Vale of Thaena. Adept at constructing magical prisons due to the Creation War (1486 DE - 8777 DE) and its Primordial dreadnoughts, the Covenant built a magical trap that ensnared Thaena and submerged him underground, where they showered him with water, both magically and by summoning a spring storm. Once in place, Thaena would be perpetually cooled by the natural streams and precipitation of the surrounding land. Considerable effort was devoted to shaping the area beneath the surface, guiding the water to the desired location. After this work was completed, the area was backfilled and laden with deadly magical traps, deterring even Lukoon from approaching.
In the Horgon Era, sensing formidable magical power in this valley, the dragon Nveryioth descended and established himself in the area above Thaena's prison. There, he and his adherents constructed the imposing castle of Khilgand.