The Fallurost Empire fell during the Bitter Invasion of the 16,000s, a terrible time when Yinram (now named Asoumiranz) was beset by gaseous black phantoms called the Thecons. The Thecons were thought to be alien invaders, presumably from some other planet. Most of the population of Yinram was wiped out between 15,997, when the Bitter Invasion began, and 16,301, when the last Thecon was finally destroyed. At some point during the Bitter Invasion, a method of destroying Thecons was discovered, and gradually refined. The resistance started around 16,037, with people reclaiming territories from the Thecons over the course of centuries. From the ashes of the Bitter Invasion, new cultures formed.
Fall of the Thecon[]
It is thought that the Thecon's focus was primarily on humans, since at the time they were the most widespread and populous race. Humans eventually discovered ways of killing Thecons, driving them away and thwarting their long reign. However, there is a large untold portion to the story as well. Thecons were a space-faring race who swept into the Other Solar System from another nearby star system. Their focus was not entirely on Otherworld itself, but also on nearby planets. Being unable to sense most types of spirits, the Heavens were mostly unaffected by the Thecons.
The main exception to this were the Momen of yellow moon, who in fact fought battles against the Thecons and took heavy losses and damage to their civilisation. However, the Thecons main foe in all this was not the humans or the Momen. It was in fact the ancestors to the modern Tin Fish. In the 16,000s the Tin Fish were a much nobler and far more powerful race than they are today. The Tin Fish fought hard against the Thecons and in fact discovered and developed many of the methods for their destruction, which they shared with humanity via long distance messages. The Tin Fish, back then, occupied many of the asteroids in the Other Solar System, consisting of a large empire. While they were, even back then, a strange and alien type of intelligence compared to humans, they were not malicious and were in fact quite noble.
They suffered heavy losses against the Thecon menace, wishing to protect Otherworld and the other planets of the solar system. The single remaining Tin Fish outpost at the end of the war was a small community, and they underwent a cultural shift over the next few millennia, leading to the villainous Tin Fish of the modern day.