The importance of the Mongol Empire and its long-term effects across Eurasia have long been an object of fascination among historians. However, little has been written about how Činggis Qan and his empire were remembered in Mongolia in the post-imperial period — that is, from 1368, when the last Mongol emperor fled his capital in Daidu (present day Beijing), until the Mongol princedoms were rolled up into the incipient Qing Empire in the first half of 1600s. For the intervening centuries (fifteenth to sixteenth), the social, cultural, and religious aspects of the Mongols remain obscure, mostly due to a dearth of sources. Yet, the idea that no text survives from that dark period'' is false, because a large body of liturgical texts has been transmitted to our times – even if largely ignored by historians – through the Cult of Činggis Qan. Today, this institution remains an active among the Mongol communities in Ordos, Inner Mongolia. In particular, men of the Darqad lineages, whose families served as hereditary shrine custodians for generations, officiating the ceremonies and driving around the cult's camel-drawn tent-carts, have published many works sharing their knowledge and family memory. In Ordos, in an area known as Eǰen Qoro'a (Mo. `Lord's Sanctuary'), the replicas of the shrine's physical artifacts, the originals of which were destroyed during the Cultural Revolution, are now the center-piece of a Museum, which is itself the focal point of a flashy tourist attraction. My dissertation includes, as an essential appendix, a critical edition along with a translation to English of the texts passed down in this Činggis Qan shrine – most of which have been published in facsimile and/or transcription by scholars in the last few decades. Based in this material as a novel primary source, the chapters are written with a goal to sharpen our understanding of the contexts in the cultic texts were produced, thus deepening the field's understanding of the social and cultural history of the `dark' period. Chapter 1 contains a literature review on the extant scholarship and sources on the Cult of Činggis Qan and related themes, like methodology on the study of religion and rituals. The manuscript witnesses of the Altan Bichig, its organization in this dissertation, and the textual criticism I have completed are introduced in Chapter 2. Since most of the manuscript witnesses are themselves collections of various texts created by or for scholars, I have arranged them in modular assemblies'' that represent how different texts were grouped together as they circulated. This is followed by a pre-history'' of the Dayan Qaġanid cult in Chapter 3, which traces the cult's existence in the historical sources on the early Mongol Empire, the Yuan Dynasty (1264-1368), and the memory of the post-imperial period as written in the sixteenth to seventeenth century Mongolian histories. Chapters 4, 5, and 6 are detailed analysis of the framework texts'' within the Altan Bichig, which are ritual instructions and ritual codes that describe how the ceremonies are to be conducted. From the peculiarities of their contents, I deduce their time and political context, and contribute new data that deepen our understanding of the Dayan Qanid court culture. A thorough understanding of these cultic texts is a necessary endeavor by itself, and it is essential for the study of Mongolian history, because the Sitz im Leben or `situation in life' that led to the composition of all sixteenth and seventeenth century histories on which the whole field relies cannot be separated from the Cult of Činggis Qan.