The shadow world
The shadow world first appears on the southern horizon of the continent in the 5th century. Slowly but surely, this "long dark shadow" as the seafarers call it, pushes towards the mainland; in the 6th century it reaches the mainland. The area beyond the shadow's border presents itself as a perverted reflection of the actual world: unsteady and unreal, it distorts life, animals and all existence as if through a broken mirror. Magnificent roses transform here into dangerous, stinging, writhing perversions that secrete an almost unbearable stench. Shallow waters turn into raging abysses and even the most harmless hare becomes a bloodthirsty beast here. It is also said that whoever dies in the shadow world, their soul will enter it and become part of this hideous chaos. Eternally it becomes trapped in the unsteady flow of perversion.
The sky in the shadow world is caught in constant chaos: Black storm clouds mingle with colours that almost seem like a blazing fire. Then everything turns a poisonous green, only to be replaced by an equally unreal yellow. No matter how the sky presents itself, however, long, threatening shadows always stretch across this desolate world.
Every now and then the "sun" shows itself: like an endless black disc it hangs in the sky, but it seems to watch you with a wary eye and never changes its position. This probably explains why the shadow world triggers an eternal unease in everyone who enters it. One always leaves under the impression of being watched by someone or something.
Anyone who wants to enter the world must use magical or clerical help. Any creature attempting to do so without such help will be driven mad or even killed by the transition alone.
With the appearance of the shadow world, the mysterious shadow cult was also founded.
Scholars of later centuries describe the shadow world as a kind of harbinger of a greater something. What exactly it might be is unknown or disputed, but it must take on horrific proportions to cast such "shadows" ahead.