The Tang Chinese inflict a devastating defeat upon the Uyghur Qaghan's forces on February 13, 843 at "Kill the Foreigners" Mountain, but the Yenisei Kyrgyz, rather than replace the Uyghurs as the lords of Mongolia, continue to live in their traditional homeland and exist as they had for centuries.

The defeat and collapse of the Uyghur Khaganate triggers a massive migration of Uyghurs from Mongolia into Turfan, Kumul, and Gansu where they found the Kingdom of Qocho and, in around 894, the Ganzhou Uyghur Kingdom.

Upper East Asia (964 – 1107 CE): 

Tangut Western Xia, Tibetan Phyi dar, and Steppe–Silk Road Crossroads

Geographic and Environmental Context

Upper East Asia comprises Mongolia, Tibet, and the western highlands of China (Xinjiang, Qinghai, Gansu, Ningxia, NW Sichuan). Landscapes range from Mongolian steppe and Gobi margins to the Tibetan Plateau and Hexi Corridor oases. Key nodes: Tarim/Turfan oases, Gansu–Ningxia irrigated towns, Qinghai/Amdo pastures, and Khams passes.

Climate and Environmental Shifts

The Medieval Warm Period modestly lengthened grazing seasons and improved barley yields in Tibetan valleys. Precipitation remained variable on the steppe; multi-year droughts strained herds and shaped diplomacy. Oases prospered on steady meltwater but faced dune encroachment and salinization—managed through constant irrigation upkeep.

Societies and Political Developments

• Tangut Western Xia (1038–1227): Mi-nyag clans consolidated the Hexi Corridor, founded the Western Xia monarchy (1038), fortified frontiers, taxed caravans, and contested borders with Northern Song and Khitan Liao.

• Oasis & Uyghur polities: Khotan fell to the Kara-Khanids (1006), accelerating Islamization in the southern Tarim; the Uyghur Kingdom of Qocho (Turfan) and Ganzhou Uyghurs remained Buddhist, sustaining manuscript culture and caravan services.

• Tibet (phyi dar, “Later Diffusion”): Post-imperial principalities backed a Buddhist renaissance—Guge and Purang patronized translation and temple building (e.g., Rinchen Zangpo; Atiśa’s arrival in 1042 spurred scholastic reform like Kadam). In Amdo/Qinghai and Khams, Tibetan and Qiangic groups balanced monastery estates with mixed pastoral–agrarian lifeways.

• Mongolia & the Eastern Steppe: No single hegemon; Kereit, Naiman, Merkit, and allied confederations engaged in horse-trade diplomacy with Song, Liao, and Western Xia.

Economy and Trade

• Caravan systems moved silk, tea, paper, porcelain, and copper cash westward; returning were horses, wool, falcons, silver, ambergris, and Islamic glass.

• Hexi tolls and forts under Western Xia monetized and secured routes.

• Tea–horse trade linked Song with Tibet/Amdo and Western Xia.

• Khotan–Kashgar reoriented toward Islamic markets; Qocho remained a Buddhist entrepôt mediating mixed networks.

Subsistence and Technology

• Pastoralism: mobile camps, composite bows, lamellar armor, and remount strings defined steppe warfare; diversified herds (horses, sheep, goats, camels, yaks) spread risk.

• Tibetan valleys: barley/buckwheat terraces, yak traction, monastery granaries, and salt trade.

• Oases: qanat/karez galleries, dams, trellised orchards (apricot, mulberry, pomegranate), and Buddhist woodblock printing (Turfan–Dunhuang).

• Frontier fortifications: Western Xia built rammed-earth walls, beacons, and river forts along caravan lanes and pastures.

Movement and Interaction Corridors

• Northern/Southern Silk Roads skirted the Taklamakan, converging through Hexi toward Song markets.

• Plateau passes (Tsang–Ngari–Purang; Qinghai Lake routes) tied Tibet to Nepal, Ladakh, and Sichuan.

• Steppe corridors linked Mongolian confederations with Liao, Western Xia, and Song horse brokers.

Belief and Symbolism

• Tibet: Buddhist phyi dar translated scriptures, built monasteries, and formed scholastic lineages; Bon persisted and hybridized locally.

• Western Xia: state Buddhism and Tangut script underpinned royal legitimacy; steles, cave shrines, and monasteries proclaimed sovereignty.

• Oases: plural religious landscape—Buddhist caves (Dunhuang), Manichaean/Nestorian enclaves among Uyghurs, and post-1006 Islamic institutions in the western Tarim.

• Steppe: sky cults, ancestor rites, and divination legitimated chieftaincy and bound camps to landscape.

Adaptation and Resilience

Pastoral mobility absorbed climate shocks; intermarriage and tribute balanced inter-tribal relations. Western Xia combined taxation with convoy protection, securing revenue without stifling flows. Tibetan monasteries acted as grain banks, schools, and diplomatic nodes; oasis irrigation and merchant diasporas kept supply chains running despite wars.

Long-Term Significance

By 1107, Upper East Asia cohered around three durable frontiers:

1. Western Xia commanding Hexi and the Ordos rim;

2. a Tibetan Buddhist renaissance radiating from Guge and Amdo/Khams;

3. Mongolian confederations refining cavalry economies ahead of 12th-century realignments.
   Xinjiang’s religious map tilted toward Islam while Qocho and Dunhuang sustained Buddhist manuscript cultures—an institutional mix that set the stage for Jin expansion, Western Xia’s apogee, and ultimately the Mongol transformations of the 13th century.