In Norse myth, what is the name of the realm of the fire giants?

In Norse myth, Muspelheim is the realm of the fire giants.

Muspelheim, also called Muspell, is a fiery region associated with heat, flame, and the beings known as the sons of Muspell. The fire giant Surtr is its most prominent ruler or guardian, carrying a sword described as brighter than the sun.

The realm plays a role in the creation of the world. In the Prose Edda, sparks and heat from Muspelheim meet the ice flowing from Niflheim across Ginnungagap, helping produce the primeval giant Ymir. This makes Muspelheim the fiery counterpart to the frozen Niflheim.

At Ragnarök, Surtr and the fire forces of Muspelheim advance against the gods. Their assault is linked to the destruction of Bifröst, and Surtr ultimately sets the world ablaze. Muspelheim is often confused with Jötunheim, the broader realm of the jötnar, or Svartalfheim, the dwarfs’ realm.