Great achievements of Songtsan Gambo
When Namri Luntsan unified the middle and lower reaches of the Yarlung Zangbo River, except for the capital city of Qoiwa Daze, he built another ruling center along the Lhasa River to administer the newly conquered areas. Tibetan historical sources say Songtsan Gambo, the son of Namri Luntsan, was born at Yarlunzhadui Palace in the Mochu Gongkar on the upper reaches of the Lhasa River (Barsam Wangtui: Question on the Chronicle of Songtsan Gambo, Tibetan Research, Vol. 1, 1995). If we accept the view that Songtsan Gambo ascended to the throne at the age of 13, there has to be at least a doubling of the years of Namri Luntsan's rule after he unified the other small kingdoms.
During this time, King Namri Luntsan made great efforts to consolidate the newly built power base. He took steps to crack down on remnant forces of local areas, and continued to launch wars against Suibi, Zhangzhung and other small kingdoms for further unification. He also made efforts to strength the position of the Tubo royal family by trying to coordinate the relationship between the new and old nobles who were engaged in incessant struggles over the distribution of royal powers. According to Tubo Historical Documents of the Dunhuang Edition, King Namri Luntsan dispatched soldiers to suppress a rebellion in the Tabo area, but he was poisoned to death by rebels. So, it was obvious that fierce struggles lasted for a long time in order to consolidate the newly established power.
There are disputes over when Songtsan Gambo was born, but scholars generally believe that his birth took place in 617, and he ascended to the throne in 629. Tubo Historical Documents, the Dunhuang Edition, say that when Songtsan Gambo came to power, subjects on his father's side were dissatisfied and resentful, while some on his mother's side openly deserted him. As the internal political situation was in a mess, Zhangzhung, Subi, Tabo, Gongbo and other small kingdoms near the Tubo Kingdom rose in rebellion against Songtsan Gambo's reign. Although he was only thirteen years old when he ascended the throne and began to handle state affairs, Songtsan Gambo showed his daring and determination by putting down the various rebellions.
Historical sources recount, "he ordered killed those who had incited rebellion along with their descendents, while try to win back those common people who once opposed him". From then on, Songtsan Gambo, generally accepted as the founder of the Tubo Kingdom with a crucial role in the development of Tibet, adopted a series of great moves with far-reaching influence in order to consolidate the newly established kingdom.