The Cosheus Abyssal marks the great “world wound” where the horde of demons was cast down in The Sundering/Bale Times. The path of the Abyssal follows the sacrifice of the 8 great cities of the Synedican Empire of the south (8 Blessings of Aerna).
Tunnels exist between Tallow’s Deep and Cosheus Abyssal.There has been a slow movement over the last thousand years to organize the orrish of the south – the abyssal provides good cover and better morale as they can see the light of the sun more. Some treasure and booty can be gained by being able to raid into the south more, and into the ruins in the abyss.
It is known that The Clearvor (Desert Giants) built the Southgate Span bridge over the Chasmlands at Southgate Garrison.
This refers to the unique environment and cultures/dwellers that have come to live inside and at the bottom of the Cosheus Abyssal.