Namri Songtsen was a member of the Yarlung tribe, located to the southeast of Lhasa, in the fertile Yarlung Valley where the Tsangpo supported both agriculture and human life. The Tibetan plateau was, at this time, a mosaic of clans of mountain shepherds with simple nomadic organizations where intertribal fighting and razzia sorties are part of the local economy. Each clan had several chiefs. These clans had few material and cultural exchanges according to topography, climate, and distances, which means that each clan, located in a specified network of valleys, had its own culture with little in common with other clans. These "proto-Tibetans" were isolated from relations with the outside world, though some mountain groups to the east in Sichuan, Qinghai and the 'Azha kingdom dwelt in border areas contiguous with, or within, the Chinese empire. Early Chinese sources appear to mention proto-Tibetan peoples in a few rare cases, if the Qiang and Rong do indeed refer to them. This changed dramatically by the beginning of Tang Dynasty, the Tibetan kingdom becoming a powerful player in the military history of Eastern and Central Asia. Several Tibetan historical accounts say that it was in Namri Songtsen's time that Tibetans obtained their first knowledge of astrology and medicine from China. Others associate the introduction of these sciences with his son. In the period, knowledge of these and other sciences came from a variety of countries, not only from China, but also from Buddhist India, Byzantium, 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. According to Beckwith, Namri Songtsen sent the first diplomatic missions to open relations with China, in 608 and 609.
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.
