From the designer:
Many years ago, the Empire of Fangs ruled the jungles of southern Arden. Their empire was built upon sacrifices to dark gods and a vicious warlike philosophy. Among those dark gods, Zengar the Fanged One received the most devoted worshippers. Called the Low Ones, they built temples in forgotten places, deep beneath the ground to be closer to their deity who dwelled in the darkest of places.
Over time, infighting and coups destroyed the empire from within. It still exists to some extent, but only as a shadow of its former self. The jungle has reclaimed many of their former cities and temples. One such temple, however, was never abandoned. The Low Ones within keep vigil over the sacred place, awaiting the day Zengar rises up to devour the unworthy.