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Reign of Tritsu Detsen (815–838)

Tritsu Detsen (Khri gtsug lde brtsan), best known as Ralpacan, is important to Tibetan Buddhists as one of the three Dharma Kings who brought Buddhism to Tibet. He was a generous supporter of Buddhism and invited many craftsmen, scholars and translators from neighbouring countries. He also promoted the development of written Tibetan and translations, which were greatly aided by the development of a detailed Sanskrit-Tibetan lexicon called the Mahavyutpatti which included standard Tibetan equivalents for thousands of Sanskrit terms.

Tibetans attacked Uyghur territory in 816 and were in turn attacked in 821. After successful Tibetan raids into Chinese territory, Buddhists in both countries sought mediation.

Ralpacan was apparently murdered by two pro- Bön ministers who then placed his anti-Buddhist brother, Langdarma, on the throne.

Tibet continued to be a major Central Asian empire until the mid-9th century. It was under the reign of Ralpacan that the political power of Tibet was at its greatest extent, stretching as far as Mongolia and Bengal, and entering into treaties with China on a mutual basis.

A Sino-Tibetan treaty was agreed on in 821/822 under Ralpacan, which established peace for more than two decades. A bilingual account of this treaty is inscribed on a stone pillar which stands outside the Jokhang temple in Lhasa.