Nirvasyl

Nirvasyl was an ancient beastman city where Shirou Oogami originates from.

History
About a thousand years ago, Nirvasyl was a beastmen-only city located somewhere in Eastern Europe. Its residents were living peacefully and doing trades with neighboring humans.

One day due to growing territorial disputes with the numerous different kinds of beastmen occupying the same territory, the high levels of stress caused the beastmen to grow bigger, monstrous-looking and more violent, and started attacking each other. This condition would later be known as Nirvasyl Syndrome.

Due to humans also getting caught in the crossfire, a general named Reymond Sylvasta, who is Alan Sylvasta's ancestor, lead an army that killed all the beastmen in the city, including Shirou. Shirou later gained immortality and a giant wolf form from the souls of the fallen beastmen and went in search of the general that killed his brethren.

With its citizens gone the city ceased to be. It's unknown how much of its history is known to beastman kind as Alan Sylvasta knew about the events that occurred, but Shirou, the sole survivor, did not.