At the time of the Dawn War, it was one of the strongest footholds of the Primordials in their battles against the Gods for control of Tol. The gods called The Thanes of the Five Halls and The Four Winds had claimed the lands of Jotunheld as their own, but their creations, the dwarves, were soon overpowered by the titans and giants that the Primordials sent to claim lands that were, at the time, fertile and good. The Northmen, warned by Hodrun the North Wind, fled in their ships across the sea to the south, rather than be captured.
Eventually, the dwarves rebelled against the giants and traveled south, through tunnels under the Frozen Sea, to their new Kingdom of Kurdenheim. This is recounted in the tales of Balgon Fivebraids. This left Jotunheld comepletely in the hands of the Primordials and their servants. Left to their own, the frost, stone, and storm giants ruined the land, leaving it a wasted desert of ice. Now, they eke a living from the land, barely a former shadow of their previous selves. Or else they war across the sea on the Northmen and dwarves.