Tride Tsugtsen
khri lde gtsug brtan / mes ag tshom (680-743)
Tride Tsugtsen, also known as Mes-Agtshom, a seven year old boy, succeeded his father. His grandmother, Trimalo, acted as Regent. Three famous temples - Drakmar Drinzang, Chimpu Namral and Drakma Keru - were constructed to the south of Lhasa during his reign. Tsugtsen married Chin-ch'eng, a daughter of a Chinese prince in 710. It was intended to smoothen relationship between Tibet and China but the attempt unfortunately failed.
In 741 the princess Chin-ch'eng Kung-chu died and the Tibetan king sent an envoy to convey the news to the Chinese emperor and at the same time expressed his desire for negotiation for peace. On the emperor’s refusal the king attacked Ch'eng-feng and marched ahead. But his advance was halted by Gen Sheng Hsi Yeh at the Cha'ang-ning bridge. Later the Tibetans captured the town of Shih-p'u and occupied it till 748. In 755 king Mes-Agtshom was killed by his ministers Bal Dongtsep and Langme Zig.
Mes-Agstom's son Trisong Detsen succeeded him the same year.
Source: http://www.tpprc.org
Since Mes-Agtshom (also known as Tride Tsugtsen or Khri-Ide-btsug-brtan) was only seven years old, his grandmother Trimalo acted as regent. Mes-Agtshom also married a Chinese princess to improve relations; but by 719 the Tibetans were trading with the Arabs and fighting together against the Chinese. In 730 Tibet made peace with China and requested classics and histories, which the Emperor sent to Tibet despite a minister's warning they contained defense strategies. During a plague in 740-41 all the foreign monks were expelled from Tibet. After the imperial princess died in 741, a large Tibetan army invaded China. Nanzhao, suffering from Chinese armies, formed an alliance with Tibet in 750. Mes-Agtshom died in 755, according to Tibetan sources by a horse accident; but an inscription from the following reign accused two ministers of assassinating him. During Trisong Detsen's reign (755-97) Tibetans collected tribute from the Pala king of Bengal and ruled Nanzhao. In 763 a large Tibetan army invaded China and even occupied their capital at Chang'an. The Chinese emperor promised to send Tibet 50,000 rolls of silk each year; but when the tribute was not paid, the war continued. In 778 Siamese troops fought with the Tibetans against the Chinese in Sichuan (Szech'uan). Peace was made in 783 when China ceded much territory to Tibet. In 790 the Tibetans regained four garrisons in Anxi they had lost to Chinese forces a century before.
Source: Sanderson Beck