This paper argues that the Classical Chinese sentence-final yun 云 is not a mere utterance particle as has been discussed. My study shows that the sentence-final yun 云 in fact serves to indicate the finality of discourse units and that yun 云 as a discourse marker is arguably descended from its full verb form meaning "to say." In its course of grammaticalization, yun 云 first develops into a quotative verb, then a quotative marker, and finally a discourse marker. At first, both of yun's 云 semantic features [+to say] and [+demonstrative] remain intact, but at the end of its grammaticalization path, yun 云 loses [+to say] and is only left with [+demonstrative]. This not only forms yun's 云 new core meaning "this" but also renders yun 云 finality as a discourse marker. The usage of yun 云 as fully fledged discourse marker can be witnessed in texts in the Han dynasty, especially in The Classic of Poetry and The Book of Han. It can be said that the use of the discourse marker yun 云characterizes the historical narrative genre, for the meaning and the function of yun 云 as predicative pronominal accord well with the narrative nature of historical records