"But Mithgar . . . Mithgar is yet wild, tempestuous, unkept, savage, turbulent, exciting. We come here to feel alive."
Mithgar is the commonly used name for the Middle Plane of existence, where the vast majority of the series' action takes place. It is derived from the old Norse name for the human world, Midgar. Though it is established that there are countless smaller planes, Mithgar is one of the major ones and lies between the horrors of Neddra and the beauty of Adonar.
Mithgar is portrayed much as medieval Europe although its stories expand out to include lands to its far east and west as well. Most of the populace is made up of human beings, but there are also substantial communities of Elves, Warrows and Chakka living in their respective habitats. Mithgar also possesses vast oceans, which the other planes don't seem to have.
It also is considered a prime place to battle the forces of Neddra, since all major wars in the series take place in the Middle Plane. Also unlike the other Planes, there seem to be several in-betweens that lead to either Neddra or Adonar, and at one time there was one to Vadaria on the island of Rwn. Since the destruction of Rwn, there is no known crossing in all of Mithgar.
The native peoples of Mithgar include human beings, Warrows, Utruni and Chakka, all of whom are able to procreate freely there. The Elves are not, and departing from Mithgar during the Ban results in permanent banishment. The same applies to creatures of Neddra such as the Ruck, the Hlok, the Ghul, the Vulg and the Ogru, and to the Mages of Vadaria.
Despite coming from a different plane, apparently Dragons and Fair Folk are able to procreate on Mithgar, although they are unable to leave without being trapped outside Mithgar. It is not clear why these are the exception.