Like Mongolia, Tibet was the center of a vast empire. Beginning in the seventh century, Tibetan armies moved north, east, and west from the area around the Yalu River in the region near present-day Lhasa. Within a few decades, they had conquered much of central Asia, including the important routes through Xinjiang used by China to trade with Western neighbors. In the eighth century the Tibetan Empire was the most feared political power in Asia. For a short period in 755, Tibetans even captured Chang'an, then the capital of China, chasing the Chinese emperor and his court from the city. Internal disputes eventually divided the Tibetan Empire, and the court's authority gave way to local leaders. However, there are lasting legacies of this imperial period. One is language. In modern China there are three dialect groups, all closely related to one another and descended from the language of the empire's armies. The first is Central Tibetan, spoken around Lhasa, in an area now called the Tibetan Autonomous Region (TAR). The second is Khams, spoken east of the TAR in Sichuan, Yunnan, and in some parts of Qinghai. The third dialect group is Amdo, spoken north of the TAR, in Qinghai, Sichuan, and Gansu provinces. Tibetan languages are also spoken in Nepal, Bhutan, and India. All of these linguistic varieties use the same written language, which is based on an alphabet invented in Tibet during the reign of Srong bstan Sgam po (627-650).
Another lasting legacy of imperial Tibet is Buddhism. The first Tibetan emperors invited Buddhist monks from India and China to teach the religion to courtiers and aristocrats. The emperors also sent learned men to India and China to gather Buddhist scriptures and translate them into Tibetan. The teachings of Buddhism took firm root, quickly permeating Tibetan society. Buddhism came to flourish in Tibet as it had nowhere else. One difference in the Buddhism of Tibet is the importance of the lama, or teacher, with whose assistance the disciple will reach spiritual enlightenment. Therefore, Tibetan Buddhism is sometimes referred to as Lamaism.
Monasteries play a key role in Tibetan society. As centers of religion, they not only minister to the spiritual needs of their lay communities but also preserve and propagate religious and scholarly traditions. In the case of Tibet, with a written history of over thirteen thousand years and thousands of religious texts, the scholarly tradition is of great significance.
In recent times Tibet's people and their culture have gained increasing attention as they wrestle with the problem of finding a political space in the rapidly changing modern world. There is concern over whether the nearly four million Tibetans living in China today will be able to hold onto their heritage and allow it to proliferate in the future.