[3] His father, Tridu Songtsen, died in 704 in battle in Mywa territory in the Kingdom of Nanzhao (Wylie: 'jang, modern lowland Yunnan).
[4] The Old Book of Tang states he was on his way to suppress tributary kingdoms on the southern borders of Tibet, including Nepal and parts of India.
[10] The Chinese Princess Jincheng (?-739), an adoptive daughter of Emperor Zhongzong of Tang (r. 705-710),[11] was sent to Tibet in 710 where, according to most sources, she married Mes-ag-tshoms, who would have been only six or seven years old at the time.
The rise of anti-Buddhist factions in Tibet following the death of the Chinese princess began to blame the epidemic on the support of Buddhism by the king and queen.
[17] Mes-ag-tshoms had two other wives, a noblewoman from the Nanam clan, Mang-mo-rje bZhi-steng, who died in 730,[18] and a princess from 'Jang (Nanzhao) called lCam lHa-spangs.
In 733 Mes-ag-tshoms wrote to the Chinese emperor Xuanzong (r. 712–756) stating that China and Tibet were equally great kingdoms and hoping that peace would endure.
In 734 a pillar engraved with the treaty was erected, and although it was apparently torn down soon after, envoys travelled regularly between the Lhasa and Chang'an for the next fifteen years.
[26] In 751 The Tibetans again sent troops north of the Jaxartes River (Syr Darya) and helped the Arabs and Qarluq Turks defeat the Chinese at Talas.
[32][33] However, the anti-Buddhist activities following the death of his Chinese wife, and some mention in the edicts of Trisong Detsen and his son Sadnalegs point to dissension and suppression of Buddhism - at least in the latter part of his reign.
[33] Mes-ag-tshoms was apparently murdered in a palace revolt sponsored by two ministers in 755, as the pillar erected later at Zhol in front of the Potala states.