Yip Goo Sing held the title of "Lord of White Cloud Castle" or "Lord of White Cloud City," depending on how you interpret the Chinese word "sing," which could mean either "castle" or "city" depending on the context. Which one did Gu Long mean it to be? If Yip Goo Sing was the lord of a castle, then he had authority over maybe a few dozen people; if he was the lord of a city, then he perhaps ruled over thousands of people, which might go some way towards explaining his desire to usurp the throne of the Ming emperor. In any case, does Gu Long ever tell us specifically what/where this "White Cloud Castle" or White Cloud City is?
Complicating things further is that BEFORE AND AFTER THE DUEL had several key scenes set at Beijing's famous White Cloud (Taoist) Monastery, which was founded by the branch of Cheun Jen Sect Taoists who had followed the teachings of Yau Chui Gei (famous in wuxia for his role in Jin Yong's L/ROCH). Despite the similarity in name, however, there doesn't seem to be any connection between the White Cloud Monastery and Yip Goo Sing's White Cloud Castle/City...or is there?