The humans in the area do not know of the Pukhan Clan's existence, aware of only local legends. 
Real World Background
Due to the revised Romanization standard of the Korean language implemented in 2000, “Pukhan” would now be known as “Bukhan” (북한).
There is no city, town or village called “Pukhan” or “Bukhan” in North or South Korea. There is Bukhan Mountain (Bukhansan) (북한산), located in the north of Seoul. It is a popular hiking spot. There is a Pukhan or Bukhan River (Bukhan Gong) (북한강), a tributary of the Han River, that flows through North and South Korea.
Pukhan or Bukhan is the shorthand name used in South Korea for the nation of North Korea. Buk (북) meaning “North” and “Han” (한) meaning “Korea.”