The Juthannan Civilization
Juthanna was an ancient kingdom or empire that was considered ahead of its time and had some unique and advanced magic. They fell to ruin, though no one knows the exact reason why, though it is suspected it had to do with arcane experiments or incurring the wrath of the gods. Juthannan relics are highly sought after, their art due to the rarity and expense making it a status symbol and how dangerous expeditions into their ruins are; while their magical relics are much less for status but for their effects as well as for study.
Much of their civilization fell into ruin.