They claim to be 'of royal descent'. [=they say that their ancestors were kings, queens, etc.]
The only path that goes down to the river is a rather steep 'descent', so be careful.
The book describes his 'descent' into a deep depression after the death of his wife.
(..) l will be among you soon. We lost it. We lost the signal. Damn! Ladies and gentlemen, we begin our descent to Fhloston. We hope you have enjoyed your flight, and hope to see you again soon. Ladies and gentlemen, welcome to Paradise. (..)1997 The Fifth Element