In the 9th century, Buddhist tradition records a contested succession, but there are many inconsistencies; contemporary Chinese histories indicate that Tibetan unity and strength were destroyed by rivalry between generals commanding the frontier armies. Early in the 9th century a scion of the old royal family migrated to western Tibet and founded successor kingdoms there, and by 889 Tibet was a mere congeries of separate lordships. In 843, during that period, Glandar-ma (reigned 841–846) ordered the suppression of Buddhism, and Tibet’s Buddhist traditions were disrupted for more than a century.

Tibetan generals and chieftains on the eastern border established themselves in separate territories. The acknowledged successors of the religious kings prospered in their migration to the west and maintained contact with Indian Buddhist universities through Tibetan scholars, notably the famous translator Rin-chen bzang-po (died 1055). In central Tibet, Buddhism suffered an eclipse. A missionary journey by the renowned Indian pandit Atisha in 1042 rekindled the faith through central Tibet, and from then onward Buddhism increasingly spread its influence over every aspect of Tibetan life.

Inspired by Atisha and by other pandits whom they visited in India, Tibetan religious men formed small communities and expounded different aspects of doctrine. Atisha’s own teaching became the basis of the austere Bka’-gdams-pa sect. The Tibetan scholar Dkon-mchog rgyal-po established the monastery of Sa-skya (1073), and a series of lamas (Tibetan priests) founded several monasteries of what is generally called the Bka’-brgyud-pa sect.

Hermits such as Mi-la ras-pa (1040–1123) shunned material things; but the systematized sects became prosperous through the support of local lords, often kinsmen of the founding lama, and, except for the Bka’-gdams-pa, each developed its own system of keeping the hierarchical succession within a noble family. In some sects the principle of succession through reincarnation was evolved. Although lamas of different schools studied amicably together, their supporters inevitably indulged in worldly competition. This tendency was intensified by the intervention of a new Asian power, the Mongols.

Although it has been widely stated that the Tibetans submitted about 1207 to Chinggis (Genghis) Khan to avert an invasion, evidence indicates that the first military contact with the Mongols came in 1240, when they marched on central Tibet and attacked the monastery of Ra-sgreng and others. In 1247, Köden, younger brother of the khan Güyük, symbolically invested the Sa-skya lama with temporal authority over Tibet. Later Kublai Khan appointed the lama ’Phags-pa as his “imperial preceptor” (dishi), and the politico-religious relationship between Tibet and the Mongol empire is stated as a personal bond between the emperor as patron and the lama as priest (yon-mchod).

A series of Sa-skya lamas, living at the Mongol court, thus became viceroys of Tibet on behalf of the Mongol emperors. The Mongols prescribed a reorganization of the many small estates into 13 myriarchies (administrative districts each comprising, theoretically, 10,000 families). The ideal was a single authority, but other monasteries, especially ’Bri-gung and Phag-mo-gru of the Bka’-brgyud-pa sect, whose supporters controlled several myriarchies, actively contested Sa-skya’s supremacy.

The collapse of the Yuan dynasty in 1368 also brought down Sa-skya after 80 years of power. Consequently, when the native Chinese Ming dynasty (1368–1644) evicted the Mongols, Tibet regained its independence; for more than 100 years the Phag-mo-gru-pa line governed in its own right.

A proliferation of scholars, preachers, mystics, hermits, and eccentrics, as well as monastic administrators and warriors, accompanied the subsequent revival of Buddhism. Literary activity was intense. Sanskrit works were translated with the help of visiting Indian pandits; the earliest codifiers, classifiers, biographers, and historians appeared. In an outburst of monastic building, the characteristic Tibetan style acquired greater extent, mass, and dignity. Chinese workmen were imported for decorative work. Temple walls were covered with fine frescoes; huge carved and painted wooden pillars were hung with silk and with painted banners (tankas). Chapels abounded in images of gold, gilded copper, or painted and gilded clay; some were decorated with stucco scenes in high relief; in others the remains of deceased lamas were enshrined in silver or gilded stupas. Under Nepalese influence, images were cast and ritual vessels and musical instruments made in a style blending exuberant power and sophisticated craftsmanship; wood-carvers produced beautiful shrines and book covers, and from India came palm-leaf books, ancient images, and bell-metal stupas of all sizes.