八思巴
The Era of Fragmentation () was an era of disunity in Tibetan history lasting from the death of the Tibetan Empire's last emperor, Langdarma, in 842 until Drogön Chögyal Phagpa became the Imperial Preceptor of the three provinces of Tibet in 1253, under the Yuan dynasty. During this period, the political unity of the Tibetan Empire collapsed following a civil war between Yumtän ("Yum brtan") and Ösung ("’Od-srung"), after which followed numerous rebellions against the remnants of imperial Tibet and the rise of regional warlords.