Cerulean was once a prison mining camp under Ironfist control. It was known as Golag pre-Starfall and is a rough ravine where prisoners died daily mining salt, copper, and obsidian. It was abandon after the Ironfisit regime was defeated by the Souls Order and left to the elements for a time.
A small group of Tieflings became tired of the treatment and persecution they receivied while living in human cities and sought out to make their own community. They took shelter within the mines tunnels and began to rebuild the broken prison into a settlement which quickly grew into a trade town. A waterfall flows through the ravine and over the exposed obsidian reflecting the town with a faint shade of blue.