The Uyghur Khaganate, self defined as the Toquz Oghuz ("Nine Tribes") and known to the Tang Chinese as the Jiuxing was a Turkic empire that existed for about a century between the mid 8th and 9th centuries. It was a tribal confederation under the Uyghur nobility.
History
Rise
In the mid-5th century, Uyghurs were a tribe of the Tiele, which was under the Turkic Khaganate.
In 657, the Western Turkic Khaganate was defeated by the Tang dynasty, after which the Uyghurs defected to the Tang. Prior to this the Uyghurs had already shown an inclination towards alliances with the Tang when they fought with them against the Tibetan Empire and Turks in 627.
In 742, the Uyghurs, Karluks, and Basmyls rebelled against the Second Turkic Khaganate.
In 744, the Basmyls captured the Turkic capital of Ötüken and killed the reigning Özmiş Khagan. Later that year, a Uyghur-Karluk alliance formed against the Basmyls and defeated them. Their khagan was killed, and the Basmyls ceased to exist as a people. Hostilities between the Uyghurs and Karluks then forced the Karluks to migrate west into Zhetysu and conflict with the Türgesh, whom they defeated and conquered in 766.
The Uyghur khagan was Kutlug I Bilge Khagan, who claimed to be the supreme ruler of all the tribes. He built his capital at Ordu-Baliq. According the New Book of Tang, the territory of the Uyghur Empire then reached "on its eastern extremity, the territory of Shiwei, on the west the Altai Mountains, on the south it controlled the Gobi Desert, so it covered the entire territory of the ancient Xiongnu".
In 745, the Uyghurs killed the last khagan of the Göktürks, Kulun Beg, and sent his head to the Tang.
Tribal composition
The Tang Huiyao, vol. 98, listed nine Toquz Oghuz surname tribes (姓部 xìngbù); another list of tribes (部落 bùluò) was recorded in the Old Book of Tang and the New Book of Tang. According to Japanese scholars Hashimoto, Katayama, and Senga, each name in the lists in the Books of Tang recorded each subtribal surname of each chief, while the other list in Tang Huiyao recorded the names of the Toquz Oghuz tribes proper. Walter Bruno Henning (1938) linked nine names recorded in the Saka language "Staël-Holstein Scroll" with those recorded by Han Chinese authors.
Golden Age
They are frugal[...] and united with one another, so their power is invincible.
In 747, Qutlugh Bilge Köl Kaghan died and was succeeded by his youngest son, Bayanchur Khan. After building a number of trading outposts with the Tang, Bayanchur used the profits to construct the capital, Ordu-Baliq, and another city further up the Selenga River, Bai Baliq. He then embarked on a series of campaigns to bring all the steppe peoples under his banner. During this time the empire expanded rapidly and brought the Sekiz Oghuz, Kyrgyz, Karluks, Türgesh, Toquz Tatars, Chiks and the remnants of the Basmyls under Uyghur rule.
In 751, the Tang Empire suffered a strategic defeat against the Arabs at the Battle of Talas. After that, the Tang retreated from Central Asia, allowing the Uyghurs to emerge as the new dominant power.
In 755 An Lushan instigated a rebellion against the Tang dynasty and in 756 Emperor Suzong of Tang turned to Bayanchur for assistance. Bayanchur agreed and ordered his eldest son to provide military service to Suzong. In 757 approximately 4,000 Uyghur horsemen assisted Tang armies in retaking Chang'an and Luoyang. After the battle at Luoyang the Uyghurs looted the city for three days and only stopped after large quantities of silk were extracted. For their aid, the Tang sent 20,000 rolls of silk and bestowed them with honorary titles. In addition the horse trade was fixed at 40 rolls of silk for every horse and Uyghurs were given "guest" status while staying in Tang China. The Tang and Uyghurs conducted an exchange marriage. Bayanchur married Princess Ninguo while a Uyghur princess was married to a Tang prince. The Uyghur Khaganate exchanged princesses in marriage with Tang dynasty China in 756 to seal the alliance against An Lushan. Bayanchur had his daughter Uyghur Princess Pijia (毗伽公主) married to the Tang prince Li Chengcai (李承采), Prince of Dunhuang (敦煌王李承采), son of Li Shouli, Prince of Bin. while the Tang princess Ningguo (寧國公主), daughter of Suzong, married Bayanchur.
In 758, the Uyghurs turned their attention to the northern Yenisei Kyrgyz. Bayanchur destroyed several of their trading outposts before defeating a Kyrgyz army and executing their khan.
On the ren-shen day of the fifth month of the first year of the Qianyuan reign [on March 29, 758 CE], The envoys from Hui-he [Uyghur Khaganate], Duo-yi-hai-a-bo and others, totaling eighty people, and an emir from the
Black-robed Dashi [Abbasid Caliphate], Nao-wen and others, totaling eight people, come at the same time to pay a visit [to the Tang court]; when they walk to the side entrance of the palace, [both delegations] argue who should be the first [to see the Emperor]. The interpreters and palace secretaries arrange them as left team and right team, and enter through the Eastern Gate and the Western Gate all at once. [After this,] Wen-she-shi and the Black-robed Dashi envoy pay their visit [to the Chinese Emperor].
In 759 the Uyghurs attempted to assist the Tang in stamping out the rebels but failed. Bayanchur died and his son Tengri Bögü succeeded him as Bögü Qaghan.
In 762 Bögü planned to invade the Tang with 4,000 soldiers but after negotiations switched sides and assisted them in defeating the rebels at Luoyang. After the battle the Uyghurs looted the city. When the people fled to Buddhist temples for protection, the Uyghurs burnt them down, killing over 10,000. For their aid, the Tang were forced to pay 100,000 pieces of silk to get them to leave. During the campaign Bögü encountered Manichaean priests who converted him to Manichaeism. From then on the official religion of the Uyghur Khaganate became Manichaeism.
Decline
In 779, Bögü Qaghan planned to invade the Tang dynasty based on the advice of his Sogdian courtiers. However, his uncle, Tun Baga Tarkhan, opposed this plan and killed him and "nearly two thousand people from among the Kaghan's family, his clique and the Sogdians." Tun Bagha Tarkhan ascended the throne, and enforced a new set of laws, which he designed to secure the unity of the khaganate. During his reign, Manichaeism was suppressed, but his successors restored it as the official religion.
In 780, a group of Uyghurs and Sogdians was killed while leaving Chang'an with tribute. Tun demanded 1,800,000 strings of cash in compensation and the Tang agreed to pay this amount in gold and silk. In 789, Tun Bagha Tarkhan died and his son succeeded him as Külüg Qaghan. The Karluks took this opportunity to encroach on Uyghur territory and annexed Futu Valley. In 790, the Uyghurs and Tang forces were defeated by Tibetan Empire at Tingzhou (Beshbalik). Külüg Qaghan died, and his son succeeded him as Qutluq Bilge Qaghan.
In 791, the Tibetans attacked Lingzhou but were driven off by the Uyghurs, who presented captured prisoners and cattle to Emperor Dezong of Tang. The Tibetans and Karluks suffered another defeat against the Uyghurs at Beiting. The captured Tibetan general Zan Rgyal Sum was sent to Dezong. In 792, the Uyghurs, led by Qutluq's son Baoyi Qaghan, defeated the Tibetans and Karluks, taking Gaochang. Not long after the Tibetans attacked Yushu, a fortified town 560 li east of Kucha. They were besieged by Baoyi there and destroyed. In 795, Qutluq Bilge Qaghan died and the Yaghlakar dynasty came to an end. A general, Qutluq II, declared himself the new qaghan, founding a new dynasty, the Ädiz (CN. Adie Chinese: 阿跌氏).
In 803, the Uyghurs captured Gaochang. In 808, Qutluq II died and his son, Baoyi Qaghan, succeeded him. In the same year, the Uyghurs seized Liang Province from the Tibetans. In 816, a Tibetan raid reached within two days' journey of Ordu-Baliq. In 821, Baoyi Qaghan died, and his son, Chongde, succeeded him. Chongde was considered the last great khagan of the Uyghur Khaganate. His achievements included improved trade up with the region of Sogdia, and on the battlefield he repulsed a force of invading Tibetans in 821. After defeating the Tibetan and Karluk force, the Uyghurs entered the Principality of Ushrusana and plundered the region. In 822, the Uyghurs sent troops to help the Tang in quelling rebels. The Tang refused the offer but had to pay them 70,000 pieces of silk to go home. In 823, the Tibetan Empire waged war on the Uyghurs. In 824, Chongde died and was succeeded by a brother, Zhaoli Qaghan. In 832, Zhaoli was murdered. He was succeeded by the son of Chongde, Zhangxin Qaghan. In the same year, the Tibetan Empire failed to make war on the Uyghurs.
Fall
In 839, Zhangxin Qaghan was forced to commit suicide and a minister named Qasar Qaghan seized the throne with the help of 20,000 Shatuo horsemen from Ordos. In the same year, there was a famine and an epidemic, with a particularly severe winter that killed much of the livestock the Uyghur economy was based on.
In 840, one of nine Uyghur ministers, Kulug Bagha, rival of Qasar, fled to the Yenisei Kyrgyz and invited them to invade from the north. With a force of around 80,000 horsemen, they sacked Ordu-Baliq, razing it to the ground. The Kyrgyz captured Qasar, and promptly beheaded him. They went on to destroy other cities throughout the Uyghur Empire, burning them to the ground. The Uyghurs fled in two groups. A 30,000-strong group led by the aristocrat Ormïzt sought refuge in Tang territory but Emperor Wuzong of Tang ordered the borders to be closed. The other group, 100,000 strong, led by Wujie Qaghan, son of Baoyi and the new khagan, also fled to Tang territory. However Wujie demanded a Tang city for residence as well as the protection of Manichaeans and food. Wuzong found the demands unacceptable and refused. He granted Ormïzt asylum in return for the use of his troops against Wujie. Two years later, Wuzong extended the order to ban Christianity, Zoroastrianism, and especially Buddhism.
The Yenisei Kyrgyz and Tang dynasty launched a successful war between 840 and 848 against the Uyghur Khaganate using their claimed familial ties as justification for an alliance.
In 841, Wujie led the Uyghurs in an invasion of today's Shaanxi.
In 843, a Tang army led by Shi Xiong attacked the Uyghurs and killed 10,000 on February 13, 843, at "Kill the Barbarians" Mountain (Shahu). Wujie was wounded. After the defeat of Wujie, Wuzong ordered Ormïzt's troops to be broken up and dispersed among different units. Ormïzt refused to obey. His troops were massacred by general Liu Mian. With the defeat of the two major Uyghur groups, Wuzong saw his chance to get rid of the Manichaeans. He ordered Manichaean temples in several cities to be destroyed, the confiscation of their estates, and the execution of the clergy.
In the fourth moon of 843, an imperial edict was issued [ordering] the Manichaean priests of the empire to be killed. [...] The Manichaean priests are highly respected by the Uighurs.
In 846, Wujie was killed after having spent his 6-year reign fighting the Kyrgyz, the supporters of his rival Ormïzt, a brother of Qasar, and Tang dynasty troops in Ordos and today Shaanxi. His brother, Enian Qaghan, was decisively defeated by Tang forces in 847.
Successors
The Yenisei Kyrgyz which replaced the Uyghur Khaganate had little interest in running the empire which they had destroyed. They held the territory from Lake Baikal in the east to the Irtysh River in the west and left Kulug Bagha, the Uyghur who defected to them, in charge of the Orkhon Valley. During the reign of Emperor Yizong of Tang (860–873), there were three recorded instances of contact between the Tang and Kyrgyz, but the nature of their relationship is unclear. Tang policy makers argued that there was no point in building any relations with the Kyrgyz since the Uyghurs no longer threatened them. The Khitans seized the Orkhon Valley from the Kyrgyz in 890 and no further opposition from the Kyrgyz is recorded.