The two kingdoms
During the earlier centuries of the Age of Construction, the North and Northwest of Rimsal were controlled by two big and powerful kingdoms that had a harmonious relationship with each other at the beginning.
One of the kingdoms was called Dagrinda and in control of Northwest Rimsal. Dagrinda was a grim country and the art of taming revisyts, which brought forth revisyt-tamers, was already known by them. However, as dark as Dagrinda was, the people there were not evil and showed much respect for those that were not put off by them. They even taught outsiders how to tame creatures that were not tamable until then because people were missing the right techniques to do so. The Dagrindans were good at coming up with new ones even if they needed to conduct dangerous tests first. They also made use of old Eophrim knowledge despite it being outdated and inferior to what Post-Eophrims came up with. Some of their knowledge was still helpful for the Dagrindans, though, and they restored many Eophrim ruins.
The other kingdom was called Ladunrur and in control of North Rimsal, eastward of Dagrinda. Unlike Dagrinda, it was much lighter in its atmosphere but less open to strangers. There are legends that the Ladunrurians were capable of using fog in different ways than what is known nowadays but that is just a myth, just like the mysterious powers that are supposed to have existed there. Powers that existed before Aptitudes were a thing and that worked without anything Essence related, apparently. This strange power, if it even existed, supposedly died out alongside Ladunrur but most historians are in agreement that this was just a myth and not real.
Relationship of the kingdoms
The two kingdoms, after they had grown to a satisfying size, were at first skeptical of each other, or rather Ladunrur was skeptical of Dagrinda. However, the other kingdom quickly overcame any wariness by sending Ladunrur a gift in the form of animals that were considered exotic there and taming techniques. The Ladunrurians were surprised but pleased by the gift and answered by sending over some of their own people and gifts. The two rulers, the current Ladunrurian king and the Dagrindan queen of that time were also fond of each other but not in a romantic way. They were highly interested in what the other kingdom had to offer and started to exchange knowledge which continued on until the Ladunrurians showed the Dagrindans the secrets to their strange powers while the Dagrindans taught them how to tame revisyts. Of course, things would turn dire at one point since both kingdoms do not exist anymore.
Occult secrets and the fog
The Ladunrurians and Dagrindans were particularly close a few centuries after they first exchanged gifts. So close that they worked together on some projects like researching ruins and conducting experiments. The last Ladunrurian king, however, showed too much interest in the occult and researched something that he just called “the northern fog”, meaning the fog from the Ocean of Mist which is close to North Rimsal, often even splashing over but, as long as it is on land, without decaying wood and rusting metal. This strangely enough only happens on the sea. The Landunrurian king thought that the fog from the Ocean of Mist must be unnatural because of its characteristics which is why he researched it. Nobody knows what results he produced because any documents he may have written are nowhere to be found or were destroyed.
Dagrinda's North also had the fog splashing over from time to time but not as much as it was the case with Ladunrur. While the Ladunrurian king was researching the fog, the last Dagrindan queen was supposedly visited by a strange and occult entity that warned her about Ladunrur. The Landururian king was about to discover something that was not supposed to be discovered by any Post-Eophrim and which was related to the Ocean of Mist. At least, that is how the legend goes but no historian believes it and characterizes it as just another myth. The queen believed the unknown entity - historians laugh about the existence of some supposed unknown entity as well - and confronted the Ladunrurian king who did not take kindly to her meddling. Most of what happened then and how their exact meeting went on was lost to time but historians believe that most of this is hogwash anyway and that the two kingdoms just had a falling out or were envious of each other. There are enough reasons why two big kingdoms started to bare fangs at each other.
The war of the two kingdoms
The two kingdoms declaring war on each other is a fact and led to a fierce conflict that went on for many years, around 60. The Dagrindan revisyt-tamers against the Ladunrurians and their strange powers while both kingdoms also had troops that were capable of what the other side could do since they shared their secrets with each other before. The war went on and on and it seemed like there would be no clear victor, both sides receiving heavy casualties. This conflict destroyed both of them and eventually led to the complete eradication of the Dagrindan and Ladunrurian kingdom. The destruction of Ladunrur also supposedly erased any traces of the powers they used but that is just another myth while the art of taming revisyts stayed alive and is even practiced today.
The vanishment of the two kingdoms led to the creation of various new countries, more than just two, that consisted of the descendants of the Dagrindans and Ladunrurians and most countries in Northwest and North Rimsal exist because of the conflict that ripped the two kingdoms apart. Examples of countries that are descendants of the two kingdoms are Pulluda, the country with the most revisyt-tamers, Abridur and others. They had nothing to do with the Atypian Empire.