The Azure Pearl, one of the three Azure Realms in the World Above. The others are Shang Qing and Tai Qing. The Azure Realms are thought to be among the oldest locations in the World Above, seemingly immune to the constant change that marks the rest of the spiritual realms. They are quite difficult to get to, as only the most powerful spirits can find the paths that lead to them.
Yu Qing is the location of Jade Mountain, a mystical reflection of Iron Mountain (or perhaps Iron is a reflection of the Jade), said to be reachable by mortals only through true spiritual enlightenment.