Which Might and Magic universe are you referring to?

By the way, plot-wise, did the Dark Knights accidentally transition into the class of Heroes who ride horses? If so, then the question is: they exist in the game.
The absence of dragons is also quite justified plot-wise. It's not that the Dark Elves haven't gained enough power to resurrect them. And it seems that in Heroes of Might and Magic V, these skeletons are somewhere in the swamps, or getting them out of there is also not a simple process. And where would you get so many dragons, and make sure they are in good condition...