Anmurim
The land of Anmurim seems normal at first. Humans and other standard races mill about their lives with minimal interference. What may come as a surprise to newcomers, however, is that every position of leadership everywhere is taken by some powerful monster.
A newcomer’s first instinct may be to save the townsfolk from these creatures, but they seem to be ok with it. That is because the monsters keep their people placated and happy (though not always ethically). Why are people fine with a beholder as their lord regent? Why has nobody questioned the zombies tilling their fields?
When questioned, the townsfolk will reveal that this has been their life for at least 1500 years. Nobody alive can remember a time before that. Their needs are met, their desires served, what's the problem?
The problem for the players (who are new to this land) is most likely the night hag running the potions shop, the vampire innkeep, and the death knight captain of the guard! Surely someone in this world has some sense?