Almost 15000 years ago, Earth suffered a huge change that almost destroyed the planet.
Humans have always been known as a greedy creature, they always have been in a position of 'power' that made them think highly about themselves, considering the human race the dominant and superior one. Maybe the race's comfort was great, but they were slowly killing the only place where they had any chance to survive.

A group of humans from all over the world started creating another type of race derived from theirs. What they didn't know, was that these experimental creatures would kill all of them and escape.

The humanoid race with no name, soon started to be called 'Spirit Folk'. Over 200 of them had escaped that day. They dispersed, destroying the old countries and unifying all of them as just dust and death lands. They were the creators of the Toxic Forests, where the survivor humans discovered that some of them, who had been having health problems, were able to survive there, but the ones that couldn't left them in the forests.

Nowadays, the Forest Folk live peacefully with the Spirit Folk as long as they don't disturb each other, which is some type of silent pact that no one dares to break. However, if someone from the big cities dares to enter the Toxic Forests, it will disturb the balance and the creatures will enrage. That happened hundreds of years ago, when a Metropolis' man went inside one of the Toxic Forests of the old Spain. The Spirit killed all the humans, leaving only the younger people of the Forest Folk alive.

That story became a preventive legend in both cultures, any Metropolitan that entered the Forest was going to be cursed by Death and would kill both human groups, the city they were from and the city in the depths of said forest. Although in the actuality, Spirit Folk will only kill outsiders.