Jotunheim is the world of the giants (two types: rock and frost, collectively called Jotuns) in the Norse Mythology. From here they menace the humans in Midgard and the gods in Asgard (from whom they are separated by the river Iving. The chief city of Jotunheim is Utgard. Gastropnir, home of Menglad, and Thrymheim, home of Thiazi, were both located in Jotunheim, which was ruled by King Thrym.