The Fu Clan's main stronghold was located deep into a mountain range in the west of Yuan Wu, The mountain range was known as the Purple Road Mountains as a purple mist sealed it off year long. Mortals are never seen again once they tread deep into the mists, and if they stayed too long within it, their throats would swell and they eyes would sting. With prolonged contact, they would even die of poison.
Although locals knew of the dangers of this mist and would well avoid it, there would always be ignorant outsiders who entered, only to perish. The Fu Clan were aware of the mortals dying from the mist, but they hardly batted an eye.
If mortals died, then so be it. The Fu Clan had planned with such great effort to create the Violet Miasma Cloud Formation, requiring them to invite several formation masters to simultaneously work on it. Besides, these mortals could be considered lucky to have died by this formation.