Longri Luntsen has established a central area in Lhasa river basin to control the new manors. He is mainly responsible for suppressing the rebel forces and unifying Tibet region. After murdered by rebels, his son Sontzen Gampo ascended the throne.
Actually, the date of Sontzen Gampo's birth is not certain. According to Tibet accounts, it is generally accepted that he was born in 617 (maybe much earlier), one year before the founding of the Tang Dynasty. He is thought to have ascended the throne at the age of thirteen. He has adopted a series of measures to consolidate the regime of Tu Bo Dynasty. Based on the measures, people praised him as the founder of Tu Bo Dynasty later.
Sontzen Gampo made the important contribution of three aspects.
Firstly, he instituted Tibetan language and the laws of Tibetan. When he took the throne, he sent royal families to India to learn philology, and then created the Tibetan language in Pinyin. Then Tibetan language has been used in public administration as soon as possible. In the meanwhile, Tibet ancient culture has been changed into a new period of developing. The enforcement of laws has insured for the dominance of royal family and noble. On the other hand, social system has been also regularized by the laws.
Secondly, a series of administrative system has been instituted. Sontzen Gampo divided four parts of "Ru" in middle and lower reaches of the Yarlung Zangbo River, and ordered officials to manage affairs over there. The four parts of Ru is similar with administration.
Thirdly, Sontzen Gampo unified most area of Qing-Tibet Plateau. During the reign of Sontzen Gampo, he was strived to unify the other tribes such as Qiang tribe (Qiang minority nationality) so that he asked for the marriage with the royal family of Tang Dynasty and the State of Nepal such as Princess Wencheng of Tang Dynasty and Princess Chizun of the State of Nepal. When Princess Wencheng and Chizun came into Tibet, they brought some technology and craft, medical books and Calendar calculation book, which improve the development of economy and politics of Tibet region. Buddhism has been introduced into Tibet by Princess Wencheng.
It's said that during the period of reign of Sontzen Gampo, the connection between Tibet and Tang Dynasty keep a good communication environment. According to Tibet record, an official of Tang Dynasty was robbed in India and fled into Tibet; Sontzen Gampo quelled the war and helped him back to Tang Empire.
After his death, his grandson Monlon Monsten took the throne, for his son died before him. There was another official who executed Sontzen Gampo's policy assisting him. They improved laws and developed Tibet while launched the war with Tang Dynasty. In the war, Tibet and Tang Dynasty were even-steven.
When Chide Zutzen who was the great-grandson of Monlon Monsten ascended the throne, he got married with Princess Jincheng of Tang Dynasty, which led a period of peace again. After Princess Jincheng came into the Tibet, there were many artisans, acrobats and many Buddhists following, which promoted the development of economy and culture of Tibet. Tibetan began to learn Chinese etiquette and folk custom. There was a stele that representative of the peace between Tibet and Tang Dynasty set up in Chiling (in Qinghai Province). But unfortunately, the war broke up many times in years. In Tibetan account, during the reign of Chide Sontzen, the region of Tibet covers vast territory.
The battle between Tibet and Tang Dynasty destroyed people's life and led to people's death, but it promoted the communication of economy and culture among nationalities on the other hand. People changed their lifestyle with daily necessities, animal by-products, clothes, crafts and activities, all of which commonly created the history of themselves.
About the history of Buddhism, Sontzen Gampo is traditionally considered to be the first people to bring Buddhism to the Tibetan people. From then on, Buddhism became the most important part in Tibetan's daily life especially during the reign of Chide Sontzen. When Londama took the throne after the death of Chide Zutzen, he held turmoil of "Disaster of Buddhism" destroying Buddha and killing Buddhist. In the next dozens of years, Tu Bo Dynasty broke up in the year of 877 in the end.