First appears in: The Splinter Soul
The Thyl Mountains are a harsh, freezing mountain range located in northern Esara on the planet Valaralda. The environment is brutal and unforgiving; as Lashel explains during their trek, "The Thyl Mountains rise steeply here, even as the latitude increases. It’s winter for long stretches of the year in these parts. Further north, we’ll encounter permafrost". Travelers facing the mountains must endure biting winds and a "blanket of brilliant white snow".
Nestled within these freezing peaks lie the ancient ruins of Thylmanas, the birthplace of the Eglaria religion and widely considered the cradle of elven civilization. Historically, the mountains were highly coveted for their vast geographical wealth, housing "legendary" mines that yielded "not only precious stones, gold and silver, but also rare metals, ingredients for advanced technology". However, following the devastating War of Secession, the region was abandoned, leaving the mountains to reclaim the crumbling stone walls, shattered pillars, and half-formed statues of the lost city.