It was built in -1800 IC by an unnamed Dragon Emperor that united the entire civilisation of Grand Cathay in this great task in order to change the destiny of his nation forever. It was completed in under a century, and is an impenetrable fortress wall, a quarter of a mile high (from Nan Gau in the west to Wei-jin in the east[1a]), that spans league upon league across the border of Cathay. In this way Cathay protects itself from Chaos invasion.[2a]