The Abyss of Ruh was a vast and mysterious natural chasm located deep within the Rift on the planet Tython. Deep within this region, exotic and rare beasts and creatures spring forth and can only be found near to the Abyss. In the times before the foundation of the Galactic Republic the Je'daii Order established itself on the planet, exploring such bizarre places and attempting to discover the mysteries of the world. Capturing several of these animals, the Je'daii transported them to the Temple of Science, called Anil Kesh, for experimentation and analysis.
The Abyss was known to be heavily surrounded with the Dark Side and as such caused madness in many who found themselves in there.