This is a setting that I think can work for the idea. If you don't like it, we can always shift to off-brand Greyhawk.

The Known World

The known world comprises a huge landmass of about seven thousand square miles, out of them only about half form part of the civilized world. In the ancient past there used to be developed settlements in the rest of the continent, but they have been lost to the darkness over the centuries. Legends of a huge unexplored sea beyond the desserts at the edge of the known world still survive to this day.

Isharaiita
Legends tell about an ancient city that was the crown Jewel of the Golden Age Empire. Contact with it was lost long ago, but hope still remains of it still standings and prosperous.

The Empire
Currently the civilized world exists under a unified government set in the city-state of Ainsya. This government organizes the bigger picture, big-scale public works, defense of the borders and religious ritual. But for the day to day business, it consists of smaller kingdoms and even some fiefdoms with a lot of relative autonomy.

Kratika
Fabled to be the old capital of the tribe of the same name, despite that, whatever remains of the Kratika lineage has diluted so far no actual Kratika survive to this day.

Wyren
A kingdom in the Frontier, home to the finest and best military academies.

Rotus
It is a smaller fiefdom, governed by a lord. It is mostly an outpost for the frontier, but contains many small and vibrant villages.

Rahasia
One of the biggest kingdoms of the region and extremely rich.

Dynthera
A mountainous area, known for its beautifully crafted exports. Most Dwarves call it their ancestral home.

Lakumia
Another rich kingdom. They consider themselves a monarchy, but by religious reasons they consider the Empress of Light as their rightful ruler. Since she is not around, they have a senate with an elected official that shares power with a high priest of the Empress of Light.

Bukhern
A smaller fiefdom ruled by the council of mages. Home to huge universities and libraries.

Vaicia
The homeland of elves, it competes in education and research with Bukhern. Home to the White  Tower

Loukan
The spiritual capitol of the world. It is ruled by the order of our Lady. A paladin order that keeps peace around the empire.

Wergveldun
This mountainous kingdom is constituted by lots of mining towns, and its mines are rich sources of silver, gold, coal, iron and diamonds.

Xunhe
A cold kingdom on the North frontier, it is about the most desolated.

Valia
A kingdom renown for its agricultural exports.

Mazen
A heavily swamped kingdom.

Licke
A third contender for the most cultured kingdom, home to many lakes rich in resources.

Mirmirek
This kingdom is a strong trader. Source of the finest clothes and fabrics valued across the empire.

Iherm
Iherm is a dangerous deserted region inside the empire, full of treacherous mountains and dangerous ravines. Only the bravest and the dumbest dare enter.

Age of Myth

The origins of the world are lost to time. But in the beginning there was only darkness and strife. There was no civilization and no peace. That changed when the Kratikans joined and together they founded the first city. Over time they prospered and spread their influence to other tribes, carrying the torch of civilization with them.

But eventually they felt it wasn't enough, their empire covered great parts of the land, but there was only so much they could do to help the barbarians. So they prayed to the skies as one, and their prayers got heard as the purest soul of the universe descended to the world. This spirit had come to bring reason and love to all peoples, however she demanded that the Kratikans relinquished their empire and their riches as a show of genuine goodwill, which they did, storing everything in a cave as an offering to the pure spirit -To date this mythical place is known as the great treasure of Narma Kirana-. This spirit then brought light and peace to everybody in the world. As a result she started being worshiped as the Empress of Light.

Peace came, but over time men grew proud, formed kingdoms, and eventually empires on war with each other.

The Second Coming and the Golden Age
A particularly ambitious Duke, whose name should not be named as he was a demon in the flesh, desired power over the nations and conducted a perverse ritual to unleash the darkness into the world.

Then the three holy princesses -who together represented the three legitimate ways of becoming a ruler- sacrificed their lives in a bid to stop the evil demon. Their sacrifice stopped him, but the darkness and chaos continued to spread. Only the return of the Empress of Light sealed the Darkness, and she stayed on the world this time, ruling with love a third of the world while being heard by all other rulers.

This was the beginning of the Golden Age, when there was no Darkness and no violence. The empress of Light mothered 9 wise rulers and then her youngest child took upon the light of the world she carried. This light was passed from mother to daughter over millennia, keeping the world in peace.

The Decay and the great Tribulations.

However, eventually the bearers of the light weren't as pure and strong of heart, and the seal over the darkness faded over time. Little by little the Darkness and the wilderness took over the kingdoms and caused chaos and war. Monsters began to roam the wild, and evil creatures appeared, among them the first Witch.

The Silver Age.

A brave man rose among the darkness, he defeated the demons and rallied the survivors. Together with his allies he established the Great Empire with Ainsya as its capital and strong fortresses on the borderlands. A trusted ally of his formed the Council of Mages with seat in Bukhern with the purpose of protecting the people from witches which started to abound, and the holy order of our Lady formed in Loukan to keep peace in the empire.

This is the current age.

The Empress of Light
The purest soul in the world. She came twice to the world to give people civilization and peace by holding off the darkness. The emperors claim to be of her descent. She is worshiped as the main deity of the pantheon
Domains: Creation, Light, Healing

The three holy princesses
They together represent love of the people, blood and marriage, the three ways to be a legitimate ruler. They are worshiped as a group and individually.
Domains: Magic, Luck, Dreams

Amshula
Domains:Passion, Perfection, Fire.

Vali
Domains: Dreams, Truth, Indulgence.

Saavi.
Domains: Ambition, Confidence, Wealth.


Lord Nashaen
Titular deity of the Kratika kingdom, he is told to be the consort of the Empress of Light, form in which he is known as the Father of Peace. He is also advocated in his role as a guard of light, Leksus the Heavenly Conqueror of Hope, patron of soldiers. Also worshiped by himself as a protector and a caretaker of the poor and defenseless.

Lord Nashaen
Domains: Protection, Healing, Freedom

Father of Peace
Domains: Moon, Cities, Creation

Leksus the Heavenly Conqueror of Hope
Domains:Zeal, Might, Destruction.


The guards of Light
They include Leksus the Heavenly Conqueror of Hope, Vixid the Passionate Healer and Grigan the Stoic. Together they were the patrons of the Golden Age Empire.

Vixid the Passionate Healer
By herself she is the patron of nature and midwives.
Domains: Healing, Nature, Air

Grigan the Stoic
On his own he is considered the patron of hopeless causes.
Domains: Darkness, Knowledge, Magic

Vixid and Grigan
Vixid and Grigan are also worshiped as a couple as the patrons and protectors of marriage
Domains: Family, Earth, Fate

The dark deities

Lothran
The bringer of the Darkness, he unleashed the dark ritual that brought forward the Darkness into the world. Despite his defeat, he became one with the darkness and is still followed by dark cults.
Domains: Darkness, Destruction, Death, Pain, Nightmares, Undeath

Sarras
Legends tell that by the time of the second coming, a powerful bandit arose and called himself the king of all thieves. Over time, he actually became a demon and was empowered by the darkness to raise as a Dark Diety.
Domains: Travel, Trickery, Ambition

The Blue Witch
It is said that sir Aran the brave vanquished an avatar of the Blue witch a few centuries ago. However, she lives on as a deity revered by mercenaries, bandits, and witches.
Domains: Moon, Magic, Death, Destruction

Humans make up the majority of the population. Elves, Dwarves, Halflings and Gnomes are well received everywhere. Half-orcs, tieflings and dragonborn are more common in the frontier kingdoms, but it is dangerous for them to be in the more populous kingdoms as people associate them with the Darkness. Half-elves are very common, in fact they outnumber Elves almost everywhere but Vaicia.

The Kratika are said to be the oldest race in the world. However, in the present day they are no longer around, but are ancestors to some people. (Hint, Kratika ancestry can manifest as psionic powers)

Magic
The Council of Mages has an official monopoly on magic. It is illegal to be a Mage without being a member of the Council or having a license issued by the Council. Only Wizards are typically given either, as all of the schools and academies are assumed to be under direct or indirect Council control. Bards normally can practice magic openly, but eventually are expected to register too.

Divine Magic as used by clerics and paladins, and even Druids is tolerated and given an automatic pass by the Council, however other forms of magic are frowned upon and will have someone labeled a witch, hunted and judged by the Council. Buyers beware.

The Army
The empire has an standing army perpetually deployed in the frontiers, fighting a defensive war against Barbarians and the creatures brought by the corruption of the Darkness. This is a conscripted army, every year a certain amount of teenage boys are levied into basic training and have to serve for ten years. It is forbidden for volunteers to join the army, as it is created and deployed based upon a delicate demographic calculation.

The Paladin orders are the main peacekeeping force within the empire, but local militias do exist.