Li Yan

Li Yan's forces attacked the remnants of the Uyghur Khaganate, which had been weakened by internal strife and Kyrgyz attacks. Tang armies defeated the Uyghurs and secured the northern border, but the campaigns drained resources.

Li Yan issued edicts ordering the destruction of thousands of Buddhist monasteries and temples. Over 260,000 monks and nuns were forced to return to lay life. Buddhist property was confiscated, and the religion's influence was severely curtailed.

As part of his anti-religious campaign, Li Yan also suppressed Manichaeism, Zoroastrianism, and Nestorian Christianity. Foreign religions were banned, and their clergy were forced to laicize. This was part of a broader effort to assert Confucian orthodoxy.

Li Yan died in 846 after consuming alchemical elixirs in pursuit of immortality. His death was likely due to heavy metal poisoning. His successor reversed many of his anti-Buddhist policies.