From Rigpa Wiki
Nyatri Tsenpo (Wyl. gnya' khri btsan po) is said to have been the first king of Tibet. According to the Omniscient Longchenpa his family lineage derived from the Shakya clan. He was born as the only son of a king in distant Eastern India, in Ujani (today's Ujjain). But the extraordinary stigma he was born with were seen by his father as negative and he decided to have him killed. Since nobody had the courage to kill the baby, they put him in a sealed brass vase, which they threw into the Ganges. It was later found by a farmer from Vaishali, who raised the child in the middle of the forest. When he told the boy what had happened to him, the prince ran away, crossing mountains and valleys until he reached Tibet near the Yarlung Valley. There people gathered and asked him who he was and where he came from. Not understanding their language, he pointed to the sky. By this, they understood that he was a king (tsenpo) who came from the sky, and they sat him on a throne (tri), which four men carried around on yokes (nya).