The Demonic Incursion

Occurring across Baelor between approximately 6000 BFA to 5960 BFA, the Demonic Incursion was a major invasion of the Prime Material Plane by demons of the Abyss. Lead by six Demon Lords, the demonic hordes caused widespread devastation across Baelor. They were eventually defeated by six heroes, each wielding one of the Blood Weapons. The event is historically important for several reasons: It destroyed most of civilization across Baelor, knocking back thousands of years of progress. It lead to a spreading of the humanoid races to other continents on Gaia, as refugees attempted to flee the demon hordes. Lastly, it set the stage for the Fey War a decade later, in which the elves tried to conquer the other races on Baelor.

Roots of the Invasion
For thousands of years after the banishment of the Dark Gods to the 9 Hells, the demons of the Abyss had warred across the endless layers of their plane, no longer bound to the will of their original masters. Seeking to conquer the Prime Material Plane, six of these Demon Lords entered into a pact with one another: Hexar, Demon Lord of Anguish; Dezzurat, Demon Lord of Fear; Shakkari, Demon Lord of Decay; Monstragar, Demon Lord of Anger; Corporia, Demon Lord of Corruption; and Zandrick, Demon Lord of Despair. Together, they secretly had their followers scour the Prime Material Plane for Abyssal Shards, essences of the Abyss itself that had been scattered across the plane when the Dark Gods first ascended from the Abyss.

The Incursion
Finding six sufficient shards, the Demon Lords tore open six portals between their layers of the Abyss and the Prime Material Plane. Their demonic hordes swarmed across Baelor, catching the civilizations of the continent by surprise. Unable to defend themselves against the onslaught of demons, most of the commoners of the land found themselves killed or enslaved by the demons, while their armies tried fruitlessly to launch a counter-attack. Within the confines of the Everglenn, the elven city-states were largely spared from the destruction, as the demons were wary of the fey magic present within the forest.

Soon after opening the portals to Baelor, the Demon Lords began to turn on one another. Their hordes fought endlessly with each other and amongst themselves, tainting the land and destroying any settlements or civilizations they came across. As Baelor burned, the Demon Lords themselves lorded over their new territory from the confines of their Abyssal layers, rarely setting foot within the Prime Material Plane for fear of provoking an attack from one of the other Demon Lords.

Fleeing the destruction on Baelor, refugees of the invasion fled to nearby lands by boat. In 5980 BFA, the first refugees landed on Kalzan. They were quickly enslaved by the Efreeti and Djinni kingdoms that ruled over most of the continent's vast Oridian Desert, and those who escaped formed tribes that wandered the desert sands. In 5975 BFA, the first humanoids from Baelor landed in the Temperate Islands. They soon began to form settlements and cities, and the islands would become important hubs for trade in the future. In 5970 BFA, as the demonic hordes began to push into the Frozen Peaks, the tribes of the mountains set sail for Fjordland, landing at Grellan's Point. Their attempt at creating a new settlement was quickly destroyed by the Winter Wolf, and the survivors formed nomadic tribes that travelled the Frostland Wastes, ancestors of the shifter tribes that would eventually come to live on the continent.

End of the Incursion
After nearly 40 years of destruction, the humanoid races of Baelor lay scattered and broken, existing in small settlements sheltered from the eyes of the demonic hordes. Seeking to end the chaos, six heroes of various races rose up to face the Demon Lords around the year 5960 BFA. Using magic and skill to sneak past the demon hordes, they made their way through the Demonic Portal and into the realm of Corporia. Catching her unaware and managing to slay her, the heroes cut out the demon lord's heart, bringing it back to the Prime Material Plane with them. As Corporia's form wasted away, the portal she had opened closed behind her, and her horde soon consumed itself as the demons gave in to their chaotic nature.

After conversing with sages from across the land, the heroes were able to craft the Demon Lord's heart into six powerful weapons. These artifacts, known as the Blood Weapons, were specifically designed for fighting demons. Using these weapons, and rallying the remaining armies of the world to their cause, these heroes slew demon after demon, making their way one by one to each of the Demon Lords. No longer able to rely on the element of surprise, one hero fell in each battle, yet slowly the slew the remaining Demon Lords. As the final Demon Lord, Zandrick, fell, the Prime Material Plane was finally freed. The remaining demons, now cut off from the Abyss and without their leaders, were destroyed by the free armies or consumed themselves.

With the last of the Demon Lords defeated, the remaining hero hid the Blood Weapons across Baelor, hoping for their power to never be needed again. But over time, many of the Blood Weapons were found, and have since traded hands many times. Only time will tell if these forces of fiend slaying will ever be needed to save the world once more.

Aftermath
Wary of the Blood Weapons, none of the remaining Demon Lords of the Abyss have since attempted an invasion of the Prime Material Plane as thorough as the Demonic Incursion. The humanoid races of the world, their lands desecrated and their cities largely destroyed, began the slow process of recovery. Though the land would eventually heal, a mere decade later the elves would take advantage of the weakened state of Baelor by attempting to conquer the other races, beginning the Fey War. Eventually peace was reached, and civilization would bloom again across the continent.