Songtsän Gampo
Around the 6th century AD, the Yarlung Valley became a society which smelted a variety of materials including iron, copper and silver to produce weapons and other objects. The 31st king of Yarlung, Namri Songtsen, was an expansionist and invaded neighbouring tribes, expanding the territory of Yarlung. The 32nd king (who was also the first emperor of Tibet), Songtsän Gampo, conquered Subi tribe, Yangtong tribe and many others and established the Tibetan Empire. Although transferred his capital city from Qiongjie to Lhasa, many of his descendant of the royal lineage still lived in the Lhoka region. He made Yungbulakang Palace his summer palace, which by this time was an important centre for Buddhism and the storage of Buddhist scriptures. In 641 AD, Gampo married Princess Wencheng of the Tang Dynasty.