After their evolution from the monkey, the primitive people of the Land of Snows at first hived by gathering wild berries and fruit. Gradually they learned to fashion bows, arrows, knives and axes to protect themselves from wild beasts, and developed fishing and hunting skills. In other words, they were already engaged in nomadic production and by degrees a rudimentary form of agriculture was starting to emerge.

       Their beliefs and social structure at that time were molded by the extremely backward mode of production. In those days, people did not understand natural phenomena and changes such as the weather, seasons, birth and death, and so they worshipped Nature, believing all earthly things were imbued with "spirits." This state of animism is called the period of primitive Bonism by Tibetan scholars. Tribes had not yet taken shape in this society and the people lived in simple communities, fixed by their geographical environment, which had no strict organization but were led by wise elders.

      How then did the first tribe come into being? This forms the subject of another interesting folk legend. The story goes that the herdsmen of the Yarlung valley one day saw a fine youth on Mt. Tsantang Goshi. When they approached him, they discovered the young man spoke a different dialect from the native inhabitants. The herdsmen did not know what should be done with the stranger, and sent messengers back to explain the situation to the rest of the community. The elders then sent twelve intelligent men to the mountain to ask the young man where he had come from. But the youth merely pointed to the sky. Believing the stranger must have descended from heaven, the twelve rejoiced and proclaimed him a "heavenly son." The leader then offered to carry the "heavenly son," and amidst rejoicing and embraces, he was brought down the mountain seated on the leader's shoulders. The community rushed forward to greet this intelligent, handsome youth from heaven and made him the chieftain of the tribe as an honor. Thus the young man became the first leader of a tribe which later became known as the Tubo tribe.

     This event is historically said to have taken place in the year 237 BC. The youth was ceremoniously given the name Nyatri Tsanpo, "the chieftain seated on the throne of a neck," referring to the manner in which he was carried down the mountain, so from then on the Tibetan kings were known as "tsanpos." Ancient Bonrecords say that Nyatri Tsanpo, the first chieftain of the Tubo tribe, was a son of the Thirteenth Generation of the Illumined Heaven who had descended to the mortal world, and so he was recognized as king by both the clans and the adherents of Bon. Thirty-two generations after Nyatri Tsanpo, the Tubo Dynasty was founded by his descendants.

      With the emergence of kings, royal palaces began to be built. In fact, the first palaces were merely ordinary houses, and to this day the ruins of a house known as the Yumbulakang can still be seen thirty kilometers from Tsetang. According to Tibetan legend, this was the first royal palace built especially for Nyatri Tsanpo the Heavenly Son. There are two different interpretation of the Yumbulakang; one goes that "Yumbu" means "mother and son" while "lagang" refers to "palace." Thus Yumbulakang is the Palace of Mother and Son. Another interpretation goes because the Yumbulakang or the Red Willow Palace was built by the ancient Tubo king, Nyatri Tsanpo, on a hillside in Yarlung, Lhoka. On this slope red willows grew from which the name of the palace was derived.

       Seven generations after Nyatri Tsanpo, there was a king named Drigum Tsanpo. His name, given to him by his name, Drigum Tsanpo met his death at the hands of one of his subjects named by deception, the assassin drove the queen into the mountains to tend sheep, took the princess for his wife by force, sent the three princes into exile to the Kongpo and Bomi regions, and made himself chief of the tribe. Later, Chatri, the second son of Drigum Tsanpo, recruited some troops and staged a comeback. After defeating Longam, he recaptured the throne and held a grand funeral for his father, erecting a mausoleum to his memory. Even from this time, interment began to appear in Tibet.

     From the story of Drigum Tsanpo it is clear that the Tubo tribe of the Yarlung Valley had already grown quite powerful by the ninth generation. With the economic progress, animal husbandry was no longer the only form of production. Agriculture and handicrafts began to rise. The gradual improvement of the tools resulted in the increase of productivity. The private property had developed in such a degree that the struggle for power and property often arose. Tobu Society, in fact, had changed from a patriarchal clan system to paternalist ruling society.