The Tibetan Empire (Tibetan: བོད་ཆེན་པོ, Wylie: bod chen po, “Great Tibet”) existed from the 7th to 9th centuries AD when Tibet was unified as a large and powerful empire, and ruled an area considerably larger than the Tibetan Plateau, stretching to parts of East Asia, Central Asia, and South Asia. Traditional Tibetan history described the exploits of a lengthy list of rulers. External corroboration is available from the 7th century in Chinese histories. From the 7th to the 9th century a series of emperors ruled Tibet. From the time of the emperor Songtsen Gampo the power of the empire gradually increased over a diverse terrain. By the reign of the emperor Ralpacan, in the opening years of the 9th century, it controlled territories extending from the Tarim basin to the Himalayas and Bengal, and from the Pamirs to what is now Chinese provinces of Gansu and Yunnan. The varied terrain of the empire and the difficulty of transportation, coupled with the new ideas that came into the empire as a result of its expansion, helped to create stresses and power blocs that were often in competition with the ruler at the center of the empire. Thus, for example, adherents of the Bön religion and the supporters of the ancient noble families gradually came to find themselves in competition with the recently introduced Buddhism. The empire collapsed into civil war in the 840s.
The power that became the Tibetan state originated at the Taktsé Castle (Wylie: Stag-rtse) in the Chingba (Phying-ba) district of Chonggyä (Phyongs-rgyas). There, according to the Old Tibetan Chronicle, a group convinced Tagbu Nyazig (Stag-bu snya-gzigs) to rebel against Gudri Zingpoje (Dgu-gri Zing-po-rje), who was, in turn, a vassal of the Zhangzhung empire under the Lig myi dynasty. The group prevailed against Zingpoje. At this point, Namri Songtsen (also known as Namri Löntsän) was the leader of a clan which one by one prevailed over all his neighboring clans. He gained control of all the area around what is now Lhasa, before his assassination around 618. This new-born regional state would later become known as the Tibetan Empire. The government of Namri Songtsen sent two embassies to the Chinese Sui Dynasty in 608 and 609, marking the appearance of Tibet on the international scene.
The historic name for the Tibetan Empire is different from Tibet’s present name. This first mention of the name Bod, the usual name for Tibet in the later Tibetan historical sources, is significant in that it is used to refer to a conquered region. In other words, the ancient name Bod originally referred only to a part of the Tibetan Plateau, a part which, together with Rtsaṅ (Tsang, in Tibetan now spelled Gtsaṅ, has come to be called Dbus-gtsaṅ (Central Tibet).
The soldiers of the Tibetan Empire wore chainmail armor and were proficient in the use of swords and lances, but were poor in archery. According to Du You (735-812) in his encyclopedic text, the Tongdian, the Tibetans fought in the following manner:
The men and horses all wear chain mail armor. Its workmanship is extremely fine. It envelops them completely, leaving openings only for the two eyes. Thus, strong bows and sharp swords cannot injure them. When they do battle, they must dismount and array themselves in ranks. When one dies, another takes his place. To the end, they are not willing to retreat. Their lances are longer and thinner than those in China. Their archery is weak but their armor is strong. The men always use swords; when they are not at war they still go about carrying swords.
The Tibetans might have exported their armor to the neighboring steppe nomads. When the Turgesh attacked the Arabs, their khagan Suluk was reported to have worn Tibetan armor, which saved him from two arrows before a third penetrated his breast. He survived the ordeal with some discomfort in one arm.
The Tibetan Empire’s officers were not employed full-time and were only called upon on an ad hoc basis. These warriors were designated by a golden arrow seven inches long which signified their office. The officers gathered once a year to swear an oath of fealty. They assembled every three years to partake in a sacrificial feast.
While on the campaign, Tibetan armies carried no provision of grain and lived on plunder.