The emergence of a Mongol state in succession to the Kereyit khanate led to the creation of the largest land-based empire in history and a new people. The Mongols and their partners deployed and elaborated shared steppe political traditions that valued trade and customized the resources of both steppe and sedentary worlds. Under Chinggis Khan’s successor Ögödei, the mission of sacred world conquest and the ideology, governing mechanisms, and fiscal policies that enabled the attainment of this mission achieved sturdy articulation. Chinggisid priorities engendered massive demographic dislocation and transfers of peoples, and new patterns of commerce to support a robust imperial culture of consumption, patronage, and display. Early qa’ans’ ideological prerogatives and attempts to assert tighter control over resources inevitably clashed with their kinfolk’s customary claims. Tensions erupted into open civil war in 1260, but the new Chinggisid communicative space across Eurasia survived the breakup of the United Empire.

Tangut script textual and visual sources dating to the late twelfth century and the thirteenth (and beyond), though mostly Buddhist in nature, are promising materials for historians of the culture and politics of the Mongol Empire. The well-known Qara-Qoto collection housed in St. Petersburg, Russia, contains materials dating well beyond 1227, the year the Tangut Xia state fell to Mongol armies. Tangut Buddhist materials are particularly promising sources for the history of printing and religion in the Yuan dynasty. The chapter describes the origin, status, dating, and accessibility of the main collections of these sources. It then summarizes the state of research on these materials.