The Human Empire
There have always been Humans on Arkain. The Human kingdoms and their allies, the Elves and Dwarves, have fought the Demons for centuries while also being attacked by orc pillagers. They had no chance against the demons and were already close to annihilation, when the Empire showed up.
They came over the Great Sea in the west and saved the kingdoms, who immediately joined the Empire in return. The Humans still fight the Demons and more and more of them join the fight against their old suppressors.
The Humans already tried to get rid of the Demons for good, but they failed. However, they continue fighting and won't stop until there are no humans or enemies of humanity anymore.
The current Emperor is Theodor the Second.
The Orcish Clans
Legends say that the Orcs hail from another continent and then spread all over the kingdoms. But not even the oldest Orcs can tell, if that's the true or the Orcs have been here all the time, just like the other races.
But it is known that the united clans attacking absolutely everything and everyone they met and conquered a large territory. It did work for a while, but not long. The other races, especially the Demons, who were very angry about that insult, brought the fight to them and massacred half of the green skins.
The Orcs had to retreat and lost much of their territory. The only reason, why half of them are still there, is that their enemies fought among each other as well.
The Orc Clans allied with the Trolls, to increase their strengh, but still didn't manage to gather an army, that was comparable to their old numbers. Since they weren't able to begin their another huge conquest, the clans stopped working together and some old rivalries amongst the clans became important again.
Still, they managed to raid the other races and remain an annoyance for the other factions. There are still many Orcs left, which could prove to be a strong force, if they'd be united under a strong leader.
The Undead Nexus
The Undead are the most mysterious race of Arkain. Of course, necromancers and necrolytes are not unknown and have always summoned some undead servants to do their bidding, but the Undead as a complete race are a mystery to all creatures.
Once, a group of mighty necromancers, who became insane because of their immense power, believed they could rule the world with an army of the Living Dead. However, only days after they began attacking the Human kingdoms, they simply vanished. Their armies were gone and only the remains of the corpses were proof, that they ever existed.
What no mortal and no Demon knows, is, that a powerful Archlich, Aridon the Watcher, self-proclaimed guardian of Arkain, took care of them. He has the ability to take control of every Undead, he wants to control. He uses this power only, to make sure, that besides him is no one, who can form a real army of Undead. He always made the Undead kill their masters and reanimated them as his loyal servants.
The only mighty Undead, not currently living on the Dead Mountain, are guarding old temples and ruins, which contain artifacts, not meant to fall in the hands of neither mortals nor Demons. Still, they all call Aridon their master.
Aridon and his Undead live on the so called Dead Mountain, which lies within the Human kingdoms. Every sent expedition on this mountain never returned, so the Humans decided to simply ignore it and built a garrison to watch over the only entrance to the mountain.
Aridon claims to be as old as the world itself and has seen the rise and fall of races and nations. His goal is to maintain the balance of the world - or at least, what he sees as balance. He stayed out of every conflict and only watched for millenia.
But recent events force Aridon to end his idleness and take action himself instead of only manipulating others. He'll have to make the world know about the Undead - and give reason to fear them.
The Demon Legions
If there are any creatures besides the Undead Lord Aridon, who are as old as Arkain itself, than it must be the Demons. These creatures have been the bane of Arkain for a long, long time. If their history contains anything else than attacking and enslaving other races, than only the Demons know about it.
Every Demon Legion is lead by its most powerful Dreadlord. Who is the one, who commands all Legions, is unknown to every non-demon.
The Demons' realm lies in the East of the continent and is seperated by a bottomless rift, the so called Void. No one, except for Demons and their slaves, has ever been on the other side of the Void. The Void is so heavy fortified by the Demons, that they managed to block every attack there. The Void is also the place where the Imperial Army was defeated during their Great Attack.
Now, the Demons seem to begin another great offensive against the other races. And this time, they are determined to be victorious and won't show any mercy.