Wikipedia
The Licchavi Princess Bhrikuti Devi, known to Tibetans as Bal-mo-bza' Khri-btsun, Bhelsa Tritsun ('Nepali consort') or, simply, Khri bTsun ("Royal Lady"), is traditionally considered to have been the first wife of the earliest emperor of Tibet, Songtsän Gampo (605? - 650 CE), and an incarnation of Tara. She was also known as "Besa", and was a princess of the Licchavi kingdom of Nepal.
Even though the historicity of Bhrikuti Devi is not certain, and no reference to her has been found among the documents discovered at Dunhuang, "there are increasing indications supporting this hypothesis." There were certainly very close relationships between Tibet and Nepal at this period and, "Such a mythological interpretation discredits in no way the historical likelihood of such a marriage...."
Many Tibetan accounts make Bhrikuti the daughter of Amshuvarma (605-621 CE), co-ruler and successor of Śivadeva I. If this is correct, the marriage to Songtsän Gampo must have taken place sometime before 624 CE. Acharya Kirti Tulku Lobsang Tenzin, however, states that Songstän Gampo married Bhrkuti Devi, the daughter of king "Angsu Varma" or Amshuvarma (Tib: Waser Gocha) of Nepal in 632.
According to some Tibetan legends, however, a Nepali king named Go Cha (identified by Sylvain Lévi as "Udayavarman", from the literal meaning of the Tibetan name) was said to have a daughter called Bri-btumn or Bhṛkuti.
"Udayavarman" was most likely the same king we know as Udayadeva, the son of Śivadeva I and later, the adopted son and heir to Aṃshuvarmā. He was also thought to be the father of Narendradeva (Tib: Miwang-Lha). If this is accepted, it means that Narendradeva and Bhrikuti Devi were brother and sister.
We do have some fairly detailed historical accounts of Narendradeva. The (Jiu) Tangshu, or Old Book of Tang, records that when the king of 泥婆羅 Nipoluo Nepal, the father of Licchavi king Naling Deva (or Narendradeva), died, an uncle (Yu.sna kug.ti = Vishnagupta) usurped the throne. "The Tibetans gave him [Narendradeva] refuge and reestablished him on his throne [in 641]; that is how he became subject to Tibet."
It is not known exactly when Bhrikuti married Songtsän Gampo, but it was presumably about the time that Narendradeva fled to Tibet (c. 621 CE), following Dhruvadeva's take-over of the throne (who, according to an inscription dated in 623, was ruling jointly with Jiṣṇugupta.)