These names roughly translate to House of Fire and House of Cold. Muspelheim and Niflheim are the original worlds. When the other seven countries did not exist, there were already kingdoms of fire and cold in the world, and giants of fire and snow already lived in them.
Niflheim actually makes more sense than "kingdom of snow". This world embodies everything that perceives. Its energy is passive, Niflheim is not able to produce fruits on its own, for this it lacks active energy. Muspelheim, on the contrary, is full of active energy, but it also cannot bear fruit without a base. Muspelheim is like yang, Niflheim is like yin. Initially different, these worlds have always been in harmony. It would seem that ice should cool the flame, and flame should extinguish the ice. But nothing like this happened - the inhabitants of these worlds never fought with each other, on the contrary, like all giants, they were allies.
It is interesting to note that Muspelheim is in some ways the most unexplored world. All other worlds were visited either by people, or by Odin, the Father of the Gods, or by Thor the Thunderer. But no one ever entered Muspelheim, guarded by Surt with a fiery sword. Niflheim, on the contrary, is more visited, Thor has been there more than once, and the character of this world is more or less clear. Snow Giants, like the Jotuns, attack Mitgard and Asgard, but with less enthusiasm. Some of them generally prefer to sit in Niflheim and not go far beyond the confines of their world.
It is also interesting to note the geographical analogies in the location of these worlds. Niflheim is located in the north, and if you remember where Scandinavia is located, it will become clear that Niflheim is nothing more than polar ice, possibly part of Greenland (it was the Vikings, by the way, who discovered this island, but were cruelly mistaken in giving it the name Green Land). In any case, it becomes clear why Niflheim appears as a sparsely populated and evil world. The story with Muspelheim is more interesting. It would seem that fire giants must be made of fire, must burn and glow. But Surtr, the only Fire Giant who is ever described, is called "burnt black." This suggests that Muspelheim is Africa, where "black-burnt giants" live. In this case, it is appropriate to assume that Muspelheim is poorly described because the Vikings were unable to penetrate into African countries.
The result of the interaction of these worlds is the Creation of the Earth. Niflheim provided the "material" - blocks of ice into which the fire of Muspelheim breathed life. This once again confirms the guess that Niflheim acts with feminine energy, and Muspelheim with masculine energy. The elements of these worlds are quite obvious - Muspelheim - Fire, Niflheim - Water. It should be noted that the Vikings do not have Water as such, only Ice exists, but in the classical division into elements, this Ice completely corresponds to Water.
Translated from Russian · original on wisdomlib.ru