北城以北歌依旧南城以南人依然
[bĕi chéng yĭ bĕi gē yī jiù nán chéng yĭ nán rén yī rán]
'North of the Northern City, the songs remain the same; south of the Southern City, people stay as before.' It reflects nostalgia for the persistence of memories and people despite the passing of time and places changing around.