Long before @Avaron the Hollow ruled Veyrath, the land was divided among ancient civilizations that understood magic far better than anyone alive today. They discovered that Veyrath itself contained enormous currents of magical energy running beneath the earth.
These currents became known as the Veins of Veyrath.
Where several Veins crossed, strange environments formed. The @Frostpeak Range became unnaturally cold, @Embers Wastes developed its volcanic power, @The Everwood Forest grew beyond normal natural limits, and places such as the @Valley of the Mist became permanently altered by magic.
This would explain why Veyrath has so many dramatically different regions relatively close together.
More importantly, many major Points of Interest were intentionally constructed over these magical intersections.