The empire assembled under Chinggis Khan from 1206 became the largest contiguous land empire in history, and Christopher Atwood's encyclopedia sets out the machinery that held it together: a decimal army organisation that broke up older tribal loyalties, a postal relay system, a script adapted from Uyghur, and a body of law.
Its religious policy was unusually consistent. Clergy of every religion were exempted from tax and from labour service, and Buddhist, Christian, Muslim and Daoist specialists were kept at court together and set to debate in front of the khan. The result was not tolerance in the modern sense but a wide procurement of blessing, and it made the empire the most religiously mixed political structure of its age. The individual khanates then converted separately. Devin DeWeese's study of the Golden Horde traces the Islamisation of the western khanate through its own narrative traditions rather than through outside chronicles.
Tibetan Buddhism entered through the Yuan court and returned decisively in the sixteenth century, when Altan Khan met Sonam Gyatso in 1578 and conferred the title Dalai Lama. Monasteries multiplied until the twentieth century, when the purges of the 1930s destroyed most of them and killed thousands of monks. Both Buddhism and the older practice have revived since 1990.