The K'tahth Mountains was a region on the planet Qo'noS which ran east to west for about 200 miles south of the First City. It was the tallest range on the Klingon homeworld with many of its peaks consisting of active volcanoes. These mountains were said to be the most difficult climbing spots on the entire world. It was this reason why the Klingon Defense Force conducted many of its training exercises amongst its cliffs and crevasses in order to bolster their recruits strength as well as their agility. (Decipher RPG module: Worlds)