The mortal plane was the sole domain of the Faerie Races that when the gods created Men, many saw them as a lesser creation and ignored them or in some cases enslaved them . As this age drew to an end, it was at the hand of huge human empires who threw down their much more magically inclined masters by sheer numbers and force of will.
Human Empires seize control over most of the world. The Tarnish Empire marches forward like locusts until finally being defeated by internal politics and infighting. Eventually falling back to it's original borders.
