Khaenri'ah was one of the few nations in Teyvat that did not trust any Gods. Because of this, during the Archon War, having received no protection from any Gods, they lived in extremely wretched conditions, forced to cower and eke out a living deep beneath the ground of Sumeru.
As the saying goes, blessing lies within misfortune, and misfortune lurks within blessing. Through a 'coincidence', the people of Khaenri'ah obtained forbidden knowledge along with a series of research materials from their predecessors, instantly treating them like precious treasures.
Furthermore, under the cover of the Death Archon, Khaenri'ah conducted research on forbidden knowledge underground, without triggering the divine wrath of the Skyfrost Nail.
Due to the extreme danger of forbidden knowledge, the people of Khaenri'ah were not fools. The mainstream practice at the time was to refine the chaotic and uncontrollable forbidden knowledge into more controllable Abyss Power, using it as the energy source to drive mechanical operations. It was safe, durable, and efficient. Even to this day, mechanical ruins of Khaenri'ah capable of autonomous movement can still be found all over Teyvat.
Because of this, Khaenri'ah's mechanical technology advanced by leaps and bounds, with all sorts of powerful machines emerging endlessly. From Ruin Guards, Ruin Graders, to Ruin Golems, from Ruin Hunters to Ruin Drakes, and even the burrowing Ruin Serpents, Khaenri'ah's national strength reached an unprecedented level of prosperity, arguably making it the strongest superpower in Teyvat.
Yet even so, Khaenri'ah did not choose to relocate to the surface despite its booming national strength. The reason was actually very simple.
First, the Archon War had already ended, and the seven victorious Gods were granted a Gnosis by the Heavenly Principles. The lands on the surface already belonged to the territory of the Seven Gods. The Seven Gods would not interfere in human conflicts within their territories, but if another nation invaded, that would be a different story.
Second, under the hint of the Death Archon, the upper echelons of Khaenri'ah all learned that the forbidden knowledge in their hands was a power unrecognized by the Heavenly Principles. Once they left the underground, the Heavenly Principles would inevitably discover this matter, and divine punishment would arrive in an instant.
Originally, as long as Khaenri'ah continued to develop in a low-profile manner, the ancient kingdom's glory could have lasted to this day. However, humans were, after all, a race that was never satisfied.
After Khaenri'ah's level of mechanical creation fell into a bottleneck, some inwardly empty scholars turned their sights to another way of using forbidden knowledge—biological modification, which was explicitly banned by the upper echelons of Khaenri'ah.
The more it was banned, the more curious they were about its secrets. Among them, the most famous was undoubtedly Khaenri'ah's strongest alchemist, Rhinedottir, known as "Gold". Compared to eroding Teyvat's creatures with forbidden knowledge, he forged a unique path, actually nurturing life with forbidden knowledge, and even succeeded.
Dragon Durin, Elynas of Fontaine, the Golden Wolflord of Inazuma, and Albedo of Mondstadt were all creations of Rhinedottir.
However, biological modification brought success, and biological modification brought failure. Due to the madness of Khaenri'ah's scholars, the secret covered up by the Death Archon for thousands of years finally erupted completely five hundred years ago, and this was the true cause of the Khaenri'ah catastrophe.
Countless monsters poured out in full force from beneath the ground of Khaenri'ah, quickly spreading across the entire Teyvat. At this time, it was impossible for the Death Archon to keep hiding it from the Heavenly Principles.
The Heavenly Principles perceived that the power classified as forbidden by itself was running rampant to such an extent without its knowledge. Greatly enraged, it soon realized that someone among its shadow avatars was deceiving it.
However, the top priority at present was to eliminate the source of forbidden knowledge and prevent it from spreading further; otherwise, the entire Teyvat would be destroyed by forbidden knowledge.
Thus, the Heavenly Principles forcefully summoned the six Gods of Teyvat, led its four shadow avatars, and descended upon Khaenri'ah simultaneously. As the incarnation of Irminsul, Greater Lord Rukkhadevata tried every possible means to prevent the erosion of Irminsul by forbidden knowledge.
Before the disaster of Khaenri'ah broke out, there happened to be a pair of blonde siblings drifting here from outside the world. After the disaster occurred, the siblings suddenly felt that the situation was ominous, so they wanted to hurry and leave this world.
However, this scene happened to be noticed by the arriving Heavenly Principles. A pair of Travelers from outside the world with extraordinary strength hurriedly fled after the disaster struck—all these signs forced the Heavenly Principles to suspect whether this matter might be related to the two of them.
Therefore, it dispatched the Space Archon to step forward and stop them from leaving. Thus began the initial story of the allogene world.
Facing this sudden disaster, although the subjects of The Seven Nations were also suffering from the ravages of monsters, the Seven Gods all possessed a macro perspective and naturally understood the weight of priorities. Therefore, without a second word, they all headed to Khaenri'ah to fight. As for the disasters in their own nations, they could only leave them to be faced by their own subjects.
One Heavenly Principles, four Sustainers, and six Gods gathered together in Khaenri'ah. Facing the mighty monsters born from forbidden knowledge in their vast hordes, even Gods as powerful as them faced extraordinary danger.
Raiden Makoto, the First Electro Archon with the weakest strength, fell first. Before her death, the Time Archon, who was on good terms with Raiden Makoto, used the power of time to miraculously make the Sacred Sakura appear in Inazuma. Raiden Makoto used her final strength and the Sacred Sakura to resist the erosion of numerous monsters, helping the people of Inazuma get through their most difficult moments.
Soon after, Egeria, the First Hydro Archon, also unfortunately fell in Vourukasha Oasis. Just like Raiden Makoto, before his death, using his final strength, his corpse transformed into the vibrant Sea of Amrita, becoming the key to purifying the filth after the Khaenri'ah catastrophe.
Before the Goddess of Flowers died, she had separated a wisp of Khvarena and handed it over to Greater Lord Rukkhadevata to raise. Greater Lord Rukkhadevata shaped this Khvarena into the appearance of a divine bird and named it Simurgh.
After the First Hydro Archon died, Simurgh drank a mouthful of water from the Sea of Amrita, vaguely feeling its mission. Afterwards, it sacrificed itself, using its own body as nourishment, thereby giving birth to the hundreds of Khvarena, which were the Pari.
Zurvan, the first Pari, following the divine bird's last wish, summoned the born Pari to suppress the monsters on the ground. Using the power of Harvisptokhm as a medium, he purified the filth in the heavens and underground with the nectar of the Sea of Amrita.
In the end, after paying a huge price, the party of the Heavenly Principles finally cleared out all the powerful monsters of Khaenri'ah one by one. Through this battle, Khaenri'ah, the strongest human nation in Teyvat, thus perished.
However, the destruction of Khaenri'ah was only a process of this battle, not the ultimate goal. The actions of the Gods in destroying Khaenri'ah were not as cruel, ruthless, and unforgivable as Dainsleif described.
Of course, if things had ended here, it would not have caused the surviving Seven Gods to have thoughts of rebelling against the actions of the Heavenly Principles. The unexpected accident occurred during the process when the Heavenly Principles took action to seal the source of forbidden knowledge.