This research project investigates the technical and pedagogical practices of medieval Chinese Buddhism by focusing on exegetical diagrams preserved in Dunhuang from the 8th to 10th centuries. Known both as fenmen tu 分門圖 (“diagram of gate-division”) and kewen 科文 (“text of analytical division”), these diagrams exemplify the liminal nature of this unique genre, which bridges the boundaries between image and text. Flourishing in medieval China and persisting into modern Buddhist practice, these diagrams provide critical insights into the epistemological foundations of Chinese Buddhist scholasticism. The study addresses three key questions: (1) What are the defining features and functions of these diagrams, and how do they facilitate knowledge organization? (2) How were they produced, transmitted, and utilized in their manuscript contexts, and what do these practices reveal about their pedagogical roles? (3) What do these diagrams disclose about the social and institutional networks of their producers and users? The project also situates Buddhist exegetical diagrams within the broader Chinese tu 圖 tradition, comparing them with diagrams from non-Buddhist traditions to analyze their divergences as scholastic tools. By exploring these diagrams as technical devices for knowledge transmission, this research shifts scholarly focus from doctrinal content to the technical savoir-faire underpinning intellectual traditions.