Faiye

Imperial Exodus was the catalyst.

They conquered the city-states of Estyr, united them as a vassal state under the Exodan flag. Estyrians put up little fight, despite their warrior heritage. After all, an Estyrian without a master is hardly living to their full potential. Their Sultanate stayed in power as more of a liaison between their people and their conquerors and trained their fighters for Exodan use only. Before long, Estyrians had been inserted into various branches of the Exodan military. From infantry to artillery, special forces and their greatest strength, the cavalry.
Estyrians believed horses to be sacred creatures that carried gods and spirits of their faith over land and sky and sea and worshiped them as such heralds. Due to their affinity for the beasts of burden, they were some of the few who could tame the ferocious war chargers known as Dragons and handle them on the field as easily as the most docile Plainsrunner mount. A Dragon was a veritable tank of a horse, a vessel filled with a bloodlust unrivaled behind fanged teeth. They made the Exodan driving force seem unstoppable, especially with expressionless riders controlling them with the tiniest flicks of wrists.

Perhaps it was the cultural need to be loyal to the ones who gave them purpose, or maybe it was the sheer fact that Estyrians very rarely emoted if they did at all, that sowed the seed of dissent among the Imperial Council of Exodus. A mere hundred and twenty years into their occupation of the city-states of Estyr, representatives for the military complex and public safety committees began to show distrust to the warrior race. Slowly, they spread their paranoia and subsequently their propaganda to keep the towering soldiers out of their capital centers, isolating them from those who had once been their allies and brethren. As expected, though confused and concerned for the sudden change of heart, Estyrians took their ostracized status in stride. That must have been the tipping point.
On the one-hundred-thirtieth anniversary of their occupation, the tension came to a head. In the early morning, the Exodan military launched the first flaming boulders over the walls of Estyr and into the heart of the city, striking the Sultanate's Palace and dropping its glimmering domes into several residential sectors.
Estyr burned to the ground in one night, the Sultanate slaughtered alongside their people. It was the only time Exodus met the full brutality of the warrior state and such betrayal awakened something in many of those defending and covering their fleeing citizens that wrote nightmares. Stories of dead Estyrians refusing to stay dead and with fangs bared like animals instead of weapons brandished like honorable soldiers tearing flesh from bone or dismembering aggressors with their bare hands persisted from the chaos and sizzling aftermath, amid the smell of burning bodies and groaning injured.
The only things left of Estyr by sunrise were the collapsed golden domes of the Sultanate and the Star Gate, the eastern gate detailed in the imagery of their faith made originally to welcome visitors and friends, now a portal to an underworld of smouldering cinders and ash. The domes can no longer be found and the Star Gate remains today a shell of its former self, its wealth stripped by greed and time to leave its stone core as a monument to the vast tomb it guards.

The Night of Fire was four hundred years ago.
It was remembered in history books as a victory quelling rebellion in Imperial Exodus, and as a reminder of the tyranny of Exodus to those outlying conquered states and the empire's neighboring nations. A cautionary tale that they could fall too under fire and brimstone.

But Estyrians are hard to kill, true to their warrior nature, and the survivors fled. Scattering to the four corners, they established nomadic clans instead of a permanent home and their descendants can be found even today if you know where to look for them. Although they are more cautious of outsiders by the stories and histories passed down for four centuries of their persecution, they are a colorful and hospitable peoples still rooted in many of their old cultural ways.
There are rumors of those who gave into the animal impulse to survive, however. The outcast dishonorables who in the wake of their disastrous downfall discovered the taste of their own kind was too great a temptation. It's said that you don't find those ones, hungry ghosts that they are, peering from the darkest shadows of worlds as a reminder of mortal depravity. No, these ones you do not find.

They find you...