This thesis examines cultural variation and the processes of cultural change that form it through a case-study of variation and invariance in the performance of Nadun, a ritual performed in fifty-three communities in the Sanchuan region of northwest China primarily by Mangghuer (Tu) but also Tiebie (Tibetan) and Qidai (Han Chinese) communities. The text begins by placing the study in its regional context and situating the research topic within the reemergence of area studies and recent discussion on Zomia and the nature of regional formation in Asian borderlands. The introductory chapter also provides details on Nadun (including a review of relevant literature), and background on the theory and method employed in the study. The second chapter of the thesis deals with the ontological foundations of Nadun – beliefs and practices centered on an opposition between malevolent ghosts and benevolent deities that can both manipulate human fortunes. This chapter also examines the impact of Dge lugs pa Buddhism on these beliefs and practices. The third chapter examines the social patterning of Nadun according to local ideologies of age, gender, kin, and territory. Local idioms of hospitality, etiquette, and festive atmosphere which pattern dyadic social relationships are also discussed. Chapter Four deals with the impact of the state upon patterns of cultural diversity and unity in China. In particular, it seeks to establish that significant elements of Nadun represent an attempt by the Qing state to render Mangghuer populations legible, conscriptable, and favorably disposed towards the state. Chapter Five examines the impact of contemporary cultural trends – modernism, globalism, and consumerism – in Sanchuan and on Nadun. This chapter in particular examines the way in which global ideologies are co-opted by locally hegemonic ideologies. This final chapter of this thesis generalizes the findings of the previous chapters into three broadly applicable conclusions. It is first suggested that cultural diversity is most accurately envisioned as noospheric diversity – diversity of ideologies or paradigms – rather than as diversity of cultural groups, an approach which dominates contemporary discourse on cultural diversity. It is secondly suggested that a further element of cultural diversity is areal diversity – diversity in the number and nature of regions created by meshworks of social processes within which ideologies circulate. The final generalizable conclusion of this thesis is that future attention should be paid to the role of certain individuals in generating cultural diversity by creating regional variations and combinations of translocal ideologies.