Millennia ago, the city-state of Trathira was founded on the foothills of Mt. Illosell. After centuries of conquest, Trathira expanded to include the surrounding plans, and the thriving metropolis that was built on the mountain plateau was renamed Tiongraf.
The gropagas greatly revere Mt. Illosell, and the Plasper word "Trathira" actually means "Land of the Tall Mountain." The mountain is commonly climbed by gropagas seeking to commune with Inglip, and a holy shrine has been established at its summit.