Abstract: A large number of representations of traditional Chinese architecture has been well preserved in the cave grottoes at Dunhuang and studied through comparison with Song building standards recorded in Yingzao fashi. Through comparative analysis and the study of historical documents, this paper explores a hitherto neglected topic—the structural component at the bottom of a tiled roof ridge. Two types of this component have already existed in the Tang dynasty. The fifirst type appears in Tang murals at Dunhuang and at architectural representations in nearby Western Xia grottos; it is often called “warp-head tile” (qiaotou tongwa) after its shape. Representations of the second type can only be seen in neighboring Japan. The original names of both types are unknown, which gave rise to misunderstandings. This paper suggests that the so-called “warp-head tile” corresponds to the watouzi (“tile head”) recorded in Yingzao fashi, which is also the name for a similar (but) wooden component in Liaodynasty architecture. The paper then demonstrates that the second type is equivalent to the toribusuma (“bird quilt”) mentioned in historical Japanese texts; this type appeared in China in the mid-Tang period and is also a fifine example of traditional Chinese tile work.