The Tangut people were an important ethnic group in northwestern China during the seventh through eleventh centuries CE. Likely related to the Tibetans, the Tanguts spoke a language from the Qiangic group of the Sino-Tibetan linguistic family. However, Tangut culture was quite similar to others on the northern steppes - peoples like the Uighurs and Jurchen (Manchu) - indicating that the Tanguts had lived in the area for some time. In fact, some Tangut clans were nomadic, while others were sedentary.
During the 6th and 7th centuries, various Chinese emperors from the Sui and Tang Dynasties invited the Tangut to settle in what is now Sichuan, Qinghai, and Gansu Provinces. The Han Chinese rulers wanted the Tangut to provide a buffer, guarding the Chinese heartland from expansion from Tibet. However, some of the Tangut clans sometimes joined their ethnic cousins in raiding the Chinese, making them an unreliable ally.
Nonetheless, the Tanguts were so helpful that in the 630s, the Tang Emperor Li Shimin, called the Zhenguan Emperor, bestowed his own family name of Li on the Tangut leader's family. Over the centuries, however, the Han Chinese dynasties were forced to consolidate further east, out of the reach of the Mongols and Jurchens.
In the void left behind, the Tanguts established a new kingdom called Xi Xia, which lasted from 1038 to 1227 CE. Xi Xia was powerful enough to levy a hefty tribute on the Song Dynasty. In 1077, for example, the Song paid between 500,000 and 1 million "units of value" to the Tangut - with one unit being equivalent to an ounce of silver or a bolt of silk.
In 1205, a new threat appeared on the borders of Xi Xia. The previous year, the Mongols had unified behind a new leader named Temujin, and proclaimed him their "oceanic leader" or Genghis Khan (Chinguz Khan). The Tanguts, however, were no walk-over even for the Mongols - Genghis Khan's troops had to attack Xi Xia six times over more than 20 years before they were able to conquer the Tangut kingdom. Genghis Khan himself died on one of these campaigns in 1225-6; the following year, the Tanguts finally submitted to Mongol rule after their entire capital was burned to the ground.
Many Tangut people assimilated into Mongol culture, while others scattered to different sections of China and Tibet. Although some of the exiles held on to their language for several centuries more, the Mongol conquest of Xi Xia essentially finished the Tanguts as a separate ethnic group.
The word "Tangut" comes from the Mongolian name for their lands, Tangghut, which the Tangut people themselves called "Minyak" or "Mi-nyag." Their spoken language and written script are both now known as "Tangut," as well. Xi Xia Emperor Yuanhao ordered the development of a unique script that could convey spoken Tangut; it borrowed from Chinese characters rather than the Tibetan alphabet, which is derived from Sanskrit.
For more information, see Imperial China, 900-1800 by Fredrick W. Mote, Cambridge: Harvard University Press, 2003.