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In page Dolpo:

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During the reign of the Ya-rtse king A-sog-lde around 1253 both Dolpo and Serib were lost to the ruler of Gungthang, mGon po lde. The latter then reunited both the Dolpo and Serib and classified them among one of three provinces of mNga' ris. It is also known from historical documents that Mongolian troops reached Dolpo to conquer this province when they conquered many parts of Tibet and finally handed over the power to the ruler of the Sakya period.