The Zhenguan era of the Tang Dynasty brought national economic prosperity and cultural advancement. Surrounded by various ethnic minorities who greatly admired this flourishing civilization, many sent envoys to establish friendly relations, pledging allegiance and offering tribute. Numerous minority leaders sought marriage alliances with the Tang imperial family, considering it an honor. To ensure peace on the frontiers and harmonious coexistence among all ethnic groups, Emperor Taizong of Tang formulated and implemented a policy of marriage alliances. For example, Emperor Taizong married his sister, Princess Hengyang, to Ashina She'er, the son of the Turkic Chuluo Khagan, and married Princess Honghua to the Tuyuhun Khagan, Nuohebo, thereby establishing friendly relations between the Tang Dynasty and the Turkic and Tuyuhun peoples.
At that time, in the southwestern region on the Qinghai-Tibet Plateau, a powerful Tibetan regime known as Tubo (bō) had emerged. Its ruler, Songtsen Gampo (the title "Zanpu" means King of Tubo), sent envoys to the Tang capital Chang'an in 634 AD, hoping to establish friendly relations with the Tang Dynasty.
From a young age, Songtsen Gampo was highly skilled in horsemanship, archery, swordsmanship, and other martial arts. He was also culturally accomplished, able to compose poetry, and was deeply beloved by the Tibetan people. Shortly after his father's death, Tibetan nobles launched a rebellion attempting to seize power. The young Songtsen Gampo calmly faced the complex situation, and with extraordinary wisdom and courage, quickly quelled the rebellion.
Songtsen Gampo sent envoys to Chang'an not only to learn the advanced culture of the Tang Dynasty but also to request a marriage alliance with the Tang imperial family. However, Emperor Taizong did not immediately agree. Fearing blame from Songtsen Gampo upon his return, the Tibetan envoy told a lie, which caused a conflict between Tubo and the Tang Dynasty. The two sides fought several battles before eventually sitting down for peaceful negotiations.
In the year 640 AD, Songtsen Gampo dispatched a delegation of over a hundred people, led by the intelligent and capable minister (Chancellor) Gar Tongtsen, bringing many treasures of gold, silver, and precious gems, to Chang'an once again to request the marriage.
When Gar Tongtsen was received by Emperor Taizong, he conveyed Songtsen Gampo's sincere wish for friendship with the Tang Dynasty and skillfully presented the young king's desire to marry a Tang princess.
Emperor Taizong greatly admired Gar Tongtsen's eloquence and demeanor, gaining a deeper understanding of Songtsen Gampo through him. From among the imperial family's daughters, Emperor Taizong selected a cultured, beautiful, and gentle young woman, bestowed upon her the title "Princess Wencheng," and promised her in marriage to Songtsen Gampo.
That Gar Tongtsen successfully completed the marriage mission was no easy feat, and to this day, a touching folk tale called "The Five Challenges for the Marriage Envoy" is still told. After Gar Tongtsen triumphantly solved a series of difficult challenges, Emperor Taizong finally tasked him with identifying Princess Wencheng from among 2,500 beautiful young women. With his sharp eyes, Gar Tongtsen immediately recognized the poised and dignified Princess Wencheng.
In the year 641 AD, Emperor Taizong sent Li Daozong, the Prince of Jiangxia and Minister of Rites, to escort Princess Wencheng to Tubo. Accompanying her were many maids, artisans, and cooks. Her rich dowry included not only gold, silver, jewels, silks, and brocades, but also grain, vegetables, fruit seeds, medicinal herbs, silkworm eggs—items that were scarce in Tubo—as well as numerous books on Confucian classics, agriculture, medicine, astronomy, calendar systems, and science and technology.
Upon hearing the news that Princess Wencheng was to marry Songtsen Gampo, the Tibetan people along the route prepared gifts and transportation to welcome and escort her. Following Tang ceremonial customs, Songtsen Gampo traveled from his capital, Lhasa (then called Luoxie), to Lake Bo'hai (present-day Ngoring Lake in Qinghai), to personally welcome Princess Wencheng and held a grand wedding ceremony there. When he met Li Daozong, he did so in the respectful manner of a son-in-law, showing deep deference.
Following this, Songtsen Gampo escorted Princess Wencheng back to Luoxie. On the 15th day of the fourth month of the Tibetan calendar that year, the people of Luoxie celebrated her arrival like a grand festival, singing and dancing to welcome her into the city.
Songtsen Gampo deeply cherished Princess Wencheng and even built a palace in Luoxie specifically for her, modeled after Tang architectural styles. To this day, statues of Songtsen Gampo and Princess Wencheng are enshrined in the Jokhang Temple and the Potala Palace in Lhasa.
After Songtsen Gampo's death in 650 AD, Princess Wencheng continued her tireless efforts to promote cultural exchange and friendly ties between the Han and Tibetan peoples. At that time, most Tang monks traveling to India to study Buddhism passed through Tubo, and some eminent monks received warm hospitality from Princess Wencheng. Having lived in Tubo for nearly forty years, Princess Wencheng made significant contributions to the development of the Tibetan economy. She had her attendants teach local people farming techniques and personally guided the trial cultivation of crops like highland barley. She requested that the Tang Dynasty send skilled artisans to help with Tubo's development. Since Princess Wencheng's arrival in Tibet, cultural exchanges between the Tang Dynasty and Tubo greatly strengthened. She became a symbol of ethnic friendship and is still deeply cherished and remembered by the local people to this day.
Several Zanpus who succeeded Songtsen Gampo continued to maintain friendly relations with the Tang Dynasty. In 710 AD, Emperor Zhongzong of Tang married Princess Jincheng to the Tubo Zanpu. In 729 AD, the Tubo Zanpu sent envoys to meet Emperor Xuanzong of Tang, expressing a desire to be one family with the Tang, wishing for peace and tranquility for all people under heaven, thus conveying the friendly feelings and aspirations of the Han and Tibetan peoples.