The Monster Kingdom was one of the two main factions during the Monster Wars (the other being was the Human Kingdom). The current ruler of the Monster Kingdom is Asgore Dreemurr. This kingdom can be seen in Undertale, where the player goes through areas in the Underground and listens to the characters tell the story of this kingdom.
In Glitchtale, we do not really know if the kingdom was officially dissolved. However, we can suppose Asgore is still the King of all monsters or at least a figurehead, because he was called a "King" during his political issues with the humans, both in My Sunshine and in Dust.
The emblem of the Monster Kingdom is the Delta Rune.
Before the events of Undertale started, humans and monsters lived in peace and shared the world as equals.
When the war came, humans feared about monsters' power. They decided to declare war over monsters and fought a battle. However, there were no casualties among humans during this battle. In the end, the Human Kingdom decided to expel almost all the monsters to the Underground, which became the "new home" for the monsters.
Also before the events of Undertale started, the monsters killed every human who fell down in the Underground until the hero emptied the Underground, either by killing or freeing every monster in it.
At the end of Continue and beyond, the monsters, having been freed by the Underground, lived among with humans in the Surface. However, the AMD disagreed with it, regardless later on in the series, the monsters would become precious allies for humans after Bete Noire attacked everybody.
Functions of the Monster Kingdom
- Uniting Monster kind.
- Tracking down humans who fell in the Underground (before).
- Developing monster population.
Monster Kingdom's Areas
- The Underground: The ancient home of the monsters after that humans deported them from the surface.
- The Core: The energy source of the Underground.