北城以北深海未眠南城以南思念不归
[bĕi chéng yĭ bĕi shēn hăi wèi mián nán chéng yĭ nán sī niàn bù guī]
The northern side beyond the North City lies un-slept deep ocean, and south of the South City, there’s longing that never returns. It expresses the theme of distant love and nostalgia over vast distances or unreachable places separated geographically, emphasizing enduring affection through hardships.