Interactions Along the Musk Routes, Ashgate 2011,pp.117-144, p. 128.</ref> and Central Asia. Upbringing and life Around 600, Namri Songtsen, one of the several Yarlung tribal chieftains, become the uncontested leader of the several Yarlung clans. Using shepherd-warriors he subdued the neighbouring tribes one after another. Expanding his rule to all of modern Central Tibet, including the Lhasa region allowed him to rule over many groups, and to begin the establishment of a centralized and strong state, with skilled troops who gained experience in their many battles in the early 7th century. This formed an important base for the later conquests by his son, which unified the whole of the Tibetan plateau. Furthermore, Namri Songtsen relocated the capitol of his kingdom to the Gyama Valley, where he built the Gyama Palace. According to Beckwith, Namri Songtsen sent the first diplomatic missions to open relations with China, in 608 and 609. Military Campaigns Namri Songtsen one leading 10,000 Strong Forces in sumpa to attack, and destroyed faster breathing with the help of sumppa Navajo disaffected to the king's bravery and sumpa Ruler chungppo bungsae jujje. After conquering Sumpa by Siege of Sumpa, Namri Songtsen took the same steps and granted the nobles territories and slaves to gain their loyalty. Toban became the largest power in the Tibetan Plateau, and by integrating central and southern Tibet into one, it achieved the effects of population increase, economic development, and military strength, and finally transformed from a tribal state into an ancient state. However, Toban was a feudal kingdom that did not develop into a centralized state in the end, and there was a limit to being a formally unified state due to the strong power of the nobles. Assassination and succession Namri Songtsen was assassinated by poisoning in 618 or 629/630, by a coup d'état which eventually failed, being crushed by Namri Songtsen's son, who developed his heritage, completing the submission of the Tibetan plateau, and, according to later histories, introduced a unified legal code, a Tibetan writing system, an archive for official records, an army, and relations with the outside world. See also Pre-Imperial Tibet History of Tibet List of emperors of Tibet Notes Sources Josef Kolmaš, Tibet and Imperial China, A Survey of Sino-Tibetan Relations up to the End of the Madchu Dynasty in 1912. Occasional paper No. 7, The Australian National University, Centre of Oriental Studies, Canberra, 1967. Page 7-11/67. (lire