Ashina Duobi

Biography

Early Years and Accession

Ashina Duobi was the third son of Yami Qaghan Ashina Rangan. Before becoming qaghan he held the title Baghatur Shad, with his ordo located north of Wuyuan. After Emperor Gaozu of Tang Li Yuan entered Chang'an, Xue Ju still controlled the Longyou region and sent Zong Luohou to capture Pingliang and establish contact with Duobi to the north. Concerned about attack from both north and south, the Tang court sent Guanglu Minister Yuwen Xin with gold and silk to negotiate and persuade Duobi to break with Xue Ju. Yuwen Xin also urged him to return to the Tang the Wuyuan territory that had formerly belonged to Sui administrator Zhang Changxun. Duobi accepted the proposal and sent Turkic troops, together with Zhang Changxun's forces, to join Li Shimin. This shows that before his accession he was already involved in military and territorial negotiations among steppe powers and competing regimes in the Central Plains.

In 620（Wude 3）, Chuluo Qaghan died. Princess Yicheng, Chuluo's wife, did not support the accession of her own son Aoshe Shad but instead installed Chuluo's younger brother Duobi. Duobi thereby inherited the qaghanate and assumed the title Illig Qaghan. After his accession, he married Princess Yicheng according to the Turkic levirate custom and appointed Shibo'bi, son of Shibi Qaghan, as Tuli Khan with authority over the eastern region. Yang Shanjing, Princess Yicheng's younger brother, and Wang Wensu, an envoy of Wang Shichong, urged Duobi to install Yang Zhengdao as a Sui prince in order to continue the Sui imperial line. Duobi accepted the proposal and thereafter continued military operations against the Tang. Because the Central Plains had not yet been fully pacified, Emperor Gaozu of Tang often responded by granting gifts and dispatching envoys to negotiate, but relations between the two sides did not stabilize. Tang historical sources describe Duobi as relying on the military strength inherited from his father and brothers, using arrogant language in correspondence with the Tang and making frequent demands.

621–623: Repeated Frontier Campaigns and Negotiations

In 621（Wude 4）, Duobi joined the Mayi leader Yuan Junzhang in attacking Yanmen and was repulsed by Li Da'en, Prince of Dingxiang. Before the battle, Duobi had detained Tang envoys including Su Gui, Zheng Yuanshu, and Zhangsun Shunde. After the defeat, he released Zhangsun Shunde and others, sent envoys to request peace, and presented several dozen jin of fish glue as a symbol of improved relations. Emperor Gaozu of Tang released Turkic envoys including Tegin Rehan and Ashide, granted gold and silk, and agreed in principle to a marriage alliance. These negotiations did not end later frontier conflict.

In 622（Wude 5）, Liu Heita brought Turkic forces into Hebei, while Duobi led 50,000 cavalry through Yanmen, besieged Bingzhou, and sent detachments to seize people from Fenzhou and Luzhou. He also dispatched several thousand cavalry toward Yuanzhou and Lingzhou. The Tang court ordered Li Jiancheng to advance by the Binzhou route and Li Shimin by the Puzhou route, while Li Zihe was sent toward Yunzhong to strike Duobi's rear and Duan Decao moved from Xiazhou to cut off his retreat. Tang forces killed or captured 500 Turkic soldiers east of the Fen River and took 2,000 horses; Xiao Yi, prefect of Fenzhou, also defeated an attacking force. Duobi briefly captured Dazhen Pass and raided as far as Hongzhou, while Yuwen Xin and Yang Shidao fought Turkic forces near Lingzhou. During a diplomatic mission, Zheng Yuanshu directly accused Duobi of breaking the alliance and argued that Tang territory was unsuitable for long-term Turkic occupation and that plunder would have to be divided among the tribes. After hearing that Li Shimin was approaching with an army, Duobi withdrew beyond the frontier.

In 623（Wude 6）, Duobi continued to raid Dingzhou, Kuangzhou, Yuanzhou, Shuozhou, and other areas together with Liu Heita, Yuan Junzhang, and allied forces, with victories and defeats on both sides. The Tang court ordered Li Jiancheng to guard the northern frontier and Li Shimin to station at Bingzhou. Turkic forces soon captured a military settlement in Daizhou, attacked Weizhou and Binzhou, and took Mayi. Duobi later requested peace and returned Mayi to the Tang. Military attacks, negotiations, and the return of captured positions repeatedly alternated along the frontier, forcing the Tang court to continue adjusting its defences.

624–626: Southern Campaigns, Tang Responses, and the Alliance of Bian Qiao

In 624（Wude 7）, Duobi attacked Yuanzhou, Shuozhou, and other areas and joined Yuan Junzhang in attacking Longzhou, Yinpan City, and Bingzhou. In the eighth lunar month, he and Tuli Khan launched a major advance south. Heavy rain in the Guanzhong region had disrupted grain transport and exhausted Tang troops, and the two sides confronted one another near Binzhou. Duobi deployed cavalry in battle formation and sent small groups forward to challenge the Tang. Li Shimin approached the front with only a little over one hundred horsemen and publicly declared that he was willing to fight a single battle. He then invoked the former alliance between himself and Tuli. Duobi consequently suspected that Tuli had a separate agreement with the Tang and sent an envoy to explain that his intention was to discuss affairs rather than fight, after which he temporarily withdrew. Li Shimin continued to divide Tuli and Duobi; after Duobi lost Tuli's support, he sent Tuli and Ashina Simo to the Tang to request peace, and Tuli and Li Shimin established a sworn brotherhood. The operation did not become a decisive battle but exposed the fragility of the internal alliance within the khaganate.

In 625, Duobi led more than 100,000 cavalry in attacks on Lingzhou, Shuozhou, Bingzhou, Luzhou, Qinzhou, and Hanzhou. Turkic forces crossed Shiling Pass and besieged Bingzhou; Tang general Zhang Jin was defeated at Dagu, Wen Yanbo was captured, and Zhang Dezheng was killed. Li Daozong, Prince of Rencheng, defeated Turkic forces at Lingzhou. The Tang court reinforced several defensive routes, restored the Twelve Armies, and strengthened frontier defences. Duobi also sent envoys to request trade at Beilou Pass, but the fighting continued.

In 626（Wude 9）, Duobi successively raided Yuanzhou, Lingzhou, Liangzhou, Jingzhou, and other areas. Tang general Chai Shao defeated a Turkic force in Qinzhou, and Yuchi Jingde inflicted another major defeat at Jingyang and captured the Turkic irkin Ashide Wumeichuo. After Emperor Gaozu of Tang transferred the throne and Li Shimin became emperor, Duobi led forces to the north bank of the Wei River near Bian Qiao and sent Zhishi Sili into the Tang court to investigate conditions. Emperor Taizong of Tang rode out through Xuanwu Gate to the Wei River with Gao Shilian, Fang Xuanling, and only a few others, where he rebuked Duobi for breaking the alliance. The main Tang army then arrived and drew up in formation. Seeing that Zhishi Sili had not returned and that the Tang forces were orderly, the Turkic side requested peace. The two sides sacrificed a white horse and swore the Alliance of Bian Qiao, after which Duobi withdrew. The Tang court subsequently ordered the return of captured people and recovered Wen Yanbo, who had been detained for a year. The Alliance of Bian Qiao resolved the immediate crisis of an army approaching Chang'an but did not end the long-term military conflict between the two sides.

627–629: Tribal Defections and Tang Preparations

In 627（Zhenguan 1）, Xueyantuo, the Uyghurs, Bayegu, and other groups formerly under Eastern Turkic control rebelled. Duobi ordered Tuli Khan to suppress them, but after Tuli was defeated and returned with only a few riders, Duobi detained and flogged him, deepening the conflict between them. Heavy snow killed large numbers of sheep and horses, and famine followed, leaving the population exposed to cold and hunger. Despite these losses, Duobi did not reduce the burdens on subordinate groups, and historical sources describe his exactions as severe. Fearing that the Tang might take advantage of the crisis, he brought troops into the Shuozhou region under the pretext of a hunting expedition. Emperor Taizong of Tang did not attack at that time, citing the continuing alliance concluded in 626.

In 628（Zhenguan 2）, Tuli came under attack from Duobi and appealed to the Tang for assistance. The Tang court debated whether to support Tuli and made preparations for possible war. Duobi also concentrated troops and watched the Tang frontier. At the same time, Duobi appointed Zhao Deyan and gradually entrusted him with government. Tang historical sources state that Zhao monopolized authority, altered traditional customs, and imposed complicated and harsh regulations. They also record that Duobi relied on certain non-Turkic advisers while distancing members of the Turkic ruling clan, and that years of warfare and exactions burdened the subordinate tribes. The defections of Xueyantuo, the Uyghurs, and other groups, internal conflict, natural disasters, and livestock losses combined to weaken Duobi's ability to mobilize his people.

In 629（Zhenguan 3）, several tribes in the northern part of the khaganate shifted allegiance to Xueyantuo and raised Inan as qaghan. Emperor Taizong of Tang recognized Inan as Zhenzhu Bilge Qaghan and granted him drums and standards, strengthening his opposition to Duobi. The Tang court then organized six armies totaling more than 100,000 men to attack the Eastern Turkic Khaganate. Li Ji, Li Jing, Chai Shao, Li Daozong, Wei Xiaojie, and Xue Wanshu advanced on separate routes through Tongmo, Dingxiang, Jinhe, Datong, Hengan, and Changwu, with Li Jing in overall command. The Tang had already taken Mayi, forcing Illig Qaghan to retreat, and nine irkins had led their people to surrender to the Tang. Bayegu, Pugu, Tongluo, and other groups, together with leaders of the Xie and Xi, also successively came to the Tang court. Most of the northern Eastern Turkic clans, meanwhile, attached themselves to Xueyantuo. Tuli, Yushe Shad, Yin-nai Tigin, and others also brought their followers over to the Tang, further breaking apart the political and military network on which Duobi's rule depended.

Defeat in 630 and Later Life in Chang'an

In the first lunar month of 630（Zhenguan 4）, Li Jing led 3,000 troops to Eyang Ridge and launched a night attack on Duobi. Duobi, alarmed, moved his ordo to Qikou. Senior chief Kang Sumi and others brought the Sui Empress Xiao and Yang Zhengdao over to the Tang. When Duobi withdrew to Iron Mountain he still had tens of thousands of followers and sent Zhishi Sili to the Tang to apologize and request submission. Emperor Taizong of Tang sent Tang Jian, An Xiuren, and others with credentials to reassure him and also ordered Li Jing to receive his submission. After joining Li Ji at Baidao, Li Jing judged that Duobi might be waiting for spring grass to grow and the horses to recover before fleeing north of the desert. He therefore decided to attack while Tang envoys were still in the Turkic camp and the opposing side's vigilance was relaxed. Li Jing marched by night, and Su Dingfang led 200 cavalry as an advance force, approaching the ordo under cover of fog. Duobi escaped first on horseback, and his followers collapsed. Tang forces killed more than 10,000 people, captured more than 100,000 men and women, and took several hundred thousand head of livestock. Li Ji then intercepted those fleeing north at Qikou and, according to the records, captured more than 50,000 people. Duobi ultimately fled to Ashina Sunishi but was later captured by deputy expedition commander Zhang Baoxiang. Princess Yicheng was killed during the fighting, and Sunishi also led his people in submitting to the Tang. The Eastern Turkic Khaganate collapsed. The result was not only the capture of the qaghan but also the cutting of his northern escape route and the separate submission of tribal leaders to the Tang or to Xueyantuo, ending the khaganate's rule as a unified political power.

Tang forces brought Duobi to Chang'an in 630（Zhenguan 4） and formally presented the captive at the imperial ancestral temple. Emperor Taizong of Tang personally listed five offenses: failing to support the Sui, repeatedly attacking the Tang, causing resentment among his tribes through warfare, plundering people and trampling crops, and delaying after agreeing to make peace. The emperor nevertheless spared Duobi's life on the basis of the Alliance of Bian Qiao and returned his family to him. Duobi was unaccustomed to living in houses and often erected a felt tent in the courtyard, where he and his family sang mournfully and wept together. Emperor Taizong originally intended to appoint him prefect of Guozhou, but Duobi declined, and he was instead appointed Senior General of the Right Guard and granted fields and a residence. In 634（Zhenguan 8）, Duobi died in Chang'an. The Tang court posthumously granted him the title Prince Guiyi and the posthumous title Huang, ordered that he be cremated according to Turkic custom, and buried him east of the Ba River.

His Accession: Dealings with Tang and the Alternation of Peace and Raids

In 620 Jieli took Princess Yicheng as his wife and made Shibobi, son of Shibi, the Tuli qaghan, "sending envoys to court to announce the death of Chuluo," whereupon Gaozu suspended court for a day and had the officials go to the hostel to condole with the envoys. The Old History describes his position at his accession: "Jieli, newly succeeding, inherited his father's and brother's resources; his troops and horses were strong, and he had the ambition to overbear China. Gaozu, the Central Plain being newly settled, had no leisure for distant enterprises and indulged him on every occasion, his gifts past counting. Jieli's words were arrogant and his demands never sated." The New History gives the motive of his raids: Princess Yicheng was a daughter of Yang Xie, whose brother Yang Shanjing had also attached himself to the Turks, and together with Wang Wensu, an envoy of Wang Shichong, he persuaded Jieli that "in former days when the brothers Qimin quarrelled for the state, they owed their restoration to Sui and their descendants their domains; today's son of heaven is not of Emperor Wen's line, and you should set up the right line to repay Sui's great kindness," which Jieli accepted, "and so raided every year"; and "trusting to his father's and brother's legacy, with keen troops and many horses, arrogant in the extreme, above all the hundred barbarians and holding China beneath his notice, he wrote in insolent terms and made many demands." Gaozu, being engaged in ordering the empire, "therefore bent the rites, was much forgiving and gave without stint, yet could not sate his boundless requests."

In the fourth month of 621 Jieli in person, with more than ten thousand horse, and Yuan Junzhang of Mayi with six thousand, attacked Yanmen and were driven off by Li Da'en, prince of Dingxiang. He had earlier detained the Tang envoys Su Gui, duke of Hanyang, Zheng Yuanshu, master of ceremonies, and Zhangsun Shunde, general of the left Xiaowei guard, and Tang had detained his envoys in turn. Beaten by Li Da'en, "he was afraid, released Shunde and asked again for peace, presenting several tens of catties of fish glue, meaning that the two states should be stuck together like it," and Gaozu, pleased, released his envoys Tele Rehan and Ashide and gave them gold and silk. Afterwards he came south again with fifty thousand horse to Fenzhou, sent several thousand more west into Ling and Yuan, invested Bingzhou and detached troops into Fen and Lu, "taking more than five thousand men and women," and withdrew beyond the passes only when he heard that Li Shimin's army had reached Puzhou. In this period Zheng Yuanshu was sent to him, when "the Turkish picked cavalry numbered several hundreds of thousands, filling the valleys for several hundred li from Jiexiu to Jinzhou"; Zheng Yuanshu reproached him to his face for breaking faith, "arguing with him so that Jieli was much ashamed," and then advised him that "Tang and the Turks differ in custom; the Turks, even with Tang land, cannot live in it. What is plundered now goes to the people and what have you from it? Better withdraw, restore the marriage alliance, and without the toil of a journey receive gold and silk in idleness, all of it into your own treasury — how does that compare with casting away the long friendship of brothers and begetting endless hatred for your descendants?" Jieli was pleased and withdrew.

The Stand at Binzhou, the Stratagem of Division, and the Bridge of Bianqiao

In the eighth month of 624 Jieli and Tuli "raised all their troops and marched south from Yuanzhou in linked camps, and wherever they went there was terror," and Li Shimin and Li Yuanji held the Binzhou road against them. Rain having fallen for days in Guanzhong and the supply road being cut, the army halted at Binzhou, and the qaghan came suddenly with ten thousand horse, formed on the Wulong slope and challenged with several hundred riders, "and the whole army turned pale." Li Shimin rode out with a hundred horse across the front and cried: "The state has done the Turks no wrong; why do you come so deep? I am the prince of Qin, and have come to settle it with the qaghan myself — and if you insist on fighting, I have only these hundred horse." Jieli laughed and did not answer; and Li Shimin rode further and said to Tuli: "You once made a covenant with me to help in time of need; have you now no fellowship of the incense-fire? Can you come out and settle it with me alone?" Tuli too did not answer. As Li Shimin was about to cross the ditch, Jieli, seeing how few his men were and hearing the words about the incense-fire, grew suspicious, and sent an envoy to say, "Let the prince not trouble himself, nor cross the water; I had no thought of fighting, only of discussing matters with the prince," and drew back a little; and Li Shimin, turning the occasion to "sow dissension," won Tuli's heart so that he would not fight, and Jieli, losing his strong support, sent Tuli and the Jabi tele Simo to sue for peace, which the emperor granted — and when Simo was presented, the emperor had him up to the imperial couch, and when Simo bowed his head and declined, the emperor said that "in seeing you I see Jieli," and Simo submitted. A great rain coming on, the Turkish "bows and arrows all slackened and spoiled, and they broke off and returned." In the same year some advised Gaozu to move the capital away from the Turks; the ministers mostly agreed, and Li Shimin alone said: "The barbarians have been China's frontier trouble since ancient times, but we have never heard of Zhou or Han moving their capital for them. Pray give me some years, and I shall take the qaghan and answer for it," and the emperor desisted; whereupon plans for the frontier went forward — Yu Yun, director of works, asking for a river fleet at Wuyuan and Lingwu to hold the crossings, Wen Yanbo, vice-minister of the secretariat, proposing the old "long ditch" against the Xiongnu, the emperor having Sang Xianhe cut a great ditch along the frontier road, and summoning boatwrights from Jiangnan and raising labourers to build warships. In 625, when Jieli attacked Ling and Shuo and beat Lin Mu, governor of Daizhou, at Xincheng, Gaozu said in anger: "Formerly, because the empire was unsettled, I was generous to the barbarians to ease my frontier. Now that they have broken faith, I shall strike and destroy them and spare nothing," and ordered the documents to the Turks to be changed from letters between equal states to edicts and rescripts. That eighth month Zhang Jin was defeated at Dagu "with his whole army lost," and Wen Yanbo, chief of staff, was taken, and "because Yanbo held a confidential post they asked him of the state's numbers and stores; he would not answer," and was removed to the Yin mountains; at Lingzhou, Li Daozong, prince of Rencheng, broke the Turks. In 626 Chai Shao broke the Turks at Qinzhou, "beheading one tele and three great generals with a thousand of their men," and the New History sums up the Turks' way as being that "in general, when they prevail they go deep, and when they fail they sue for peace, and think no shame of it." That seventh month Jieli came in person with a hundred thousand horse against Wugong, the capital was placed under martial law, he attacked Gaoling, and Yuchi Jingde defeated him at Jingyang, taking his shad, Ashide Wumo Chi.

The Covenant at the Bianqiao Bridge and the Break-up of the Turkish Qaghanate

In the eighth month of 626 Jieli came to the north bank of the Wei at the Bianqiao bridge and "sent his confidant Zhishi Sili to court to see its real state." Zhishi Sili boasted that "the two qaghans Jieli and Tuli have a million troops and are here already," and Taizong reproached him: "I made peace face to face with your qaghan and gave him gold and silk past counting. Your qaghan has broken the covenant and led his troops deep in — is he not ashamed before me? Though you are a barbarian you have a human heart; how can you wholly forget the great kindness and boast of your strength? I shall have you killed first of all." Sili, frightened, begged for his life, and the emperor would not release him but imprisoned him in the chancellery. The emperor then went out of the Xuanwu gate himself with Gao Shilian, Fang Xuanling and six riders to the Wei, and spoke across the water with Jieli, reproaching him for breaking faith, "and the Turks were greatly astonished and all dismounted and bowed"; presently the armies came up "with banners and armour covering the plain," and Jieli, seeing that Zhishi Sili did not return and that the emperor had come out lightly and his array was imposing, showed fear. The emperor "waved the armies back to form their line and stayed alone to speak with Jieli," and when Xiao Yu, holding his bridle, remonstrated against such contempt of the enemy, Taizong answered: "My reckoning is made and it is not for you to know it... had I shown weakness and shut the gates, the enemy would have plundered at will beyond all control. Therefore I rode out alone to show that I feared nothing, displayed the splendour of the army so that they should know we must fight, and did what they did not expect, so that their plans miscarried. Deep in our country they must have fear, and so if we fight we win and if we make peace it holds." On the thirtieth day of the eighth month Taizong and Jieli "killed a white horse and swore the covenant on the Bianqiao bridge," and Jieli withdrew. Asked by Xiao Yu why he had not fought, Taizong answered that the Turkish troops were many but undisciplined and their ruler and chiefs thought only of profit, that "the qaghan is west of the water while his chiefs came to me — had I made them drunk and seized them it would have been easy as turning my hand," that he had already sent Zhangsun Wuji and Li Jing to lie in wait, so that a pursuit and an ambush would have made victory certain; but "I have newly come to the throne, and in the way of governing a state tranquillity is the first thing; a battle with the Turks would kill and wound many," and "if they were beaten but not destroyed and sued for friendship out of fear, the grudge against us would be deep"; so "I withdrew and did not fight, bribing them with gold and silk; they will certainly become arrogant, and arrogance is the beginning of destruction" — which is the principle of "giving in order to take."

What followed bore out the judgment. In the first year of Zhenguan (627) the Xueyantuo, Uighurs and Bayegu all rebelled; Jieli sent Tuli against them, he was beaten and came back with light horse, and "Jieli in anger imprisoned him for more than ten days and flogged him, so that Tuli bore a grudge"; and when Jieli several times demanded troops of him, Tuli not only refused but "memorialized asking to come to court." That year there was a great snow and "many sheep and horses froze to death," and the Turks, "fearing that the imperial armies would take advantage of their weakness, led troops into Shuozhou, claiming a great hunt." When some proposed reproaching him for breaking the covenant and attacking, Taizong said: "A common man cannot be faithless, and how much less a state? Having made a covenant with them, shall I profit by their calamity and take them at a disadvantage? Let him first be insolent to me and then I shall attack." To the proposal to build the old long wall and fill the frontier forts, Taizong listed four reasons the Turks must perish: frost and ice in midsummer and portents in the sky with "disasters frequent yet no cultivation of virtue"; horses and cattle dying in numbers without reverence for the earth; departure from the old custom of cremation to build tombs, "cheating the ghosts and spirits"; and the enmity of Jieli and Tuli, "attacking and killing one another" — whence "what need to build barriers and fill the forts?" Turkish government was itself decaying: Jieli, esteeming the Chinese Zhao Deyan, let him gradually take charge of state affairs, and gave power to Huren tribes rather than his own clan, campaigning into the frontier every year so that "his subordinates could not bear the hardship," while with "famine severe and taxes heavy, all the tribes began to harbour divided loyalties." When the Tang armies went beyond the passes after 629, Jieli's defeat and capture and removal to Chang'an were the bursting out of just these defections and accumulated ills.

An Outline of His Life

Ashina Duobi was a khan of the Eastern Turks, brother of the Chuluo khan and son of the Qimin khan. When Chuluo died in the third year of Wude, Duobi succeeded him and took the title of Illig khan. Inheriting the noonday of Turkish power with a million bowmen, he often raided the northern frontier of Tang with horsemen, and from Wude down to the early Zhenguan years his inroads came year after year, and the country between Mayi, Taiyuan and Bingzhou suffered again and again; further, leaning on Turkish strength, he harboured the divided hosts of Liu Wuzhou, Liang Shidu and Liu Heita, and was the great affliction of the north in the first years of Tang. In the fourth year of Zhenguan Tang sent Li Jing, Li Ji and others north against him by several roads; Li Jing made a night raid on the Yin Mountains, Illig fled in defeat and sought to join the Tuyuhun, but was seized by the great chief Su Ni-shi and sent to Chang'an, and the Eastern Turkish khanate perished from that time. Taizong pardoned his offence, lodged him under the court of the imperial stud, gave him the post of general of the right guards, and he afterwards died in Chang'an, being granted the title of Prince of Guiyi and the posthumous name Huang.

Major Activities

Warfare against the Tang and Frontier Negotiations

Relations between the Eastern Turkic Khaganate and the Tang during Duobi's reign were not a single uninterrupted sequence of attacks but repeatedly alternated among military pressure, battlefield setbacks, and negotiation. After the setback at Yanmen, he released some Tang envoys and presented fish glue while requesting peace. In 622（Wude 5）, he launched a major attack on Bingzhou and other areas but withdrew after facing Tang operations on several routes and negotiations by Zheng Yuanshu. In 623（Wude 6）, he returned Mayi after capturing it. In 624（Wude 7）, he advanced south with Tuli and temporarily withdrew after Li Shimin publicly challenged him and created distrust between Duobi and Tuli. In 625（Wude 8）, Turkic forces crossed Shiling and besieged Bingzhou. The Tang suffered setbacks including Zhang Jin's defeat and Wen Yanbo's capture, while Li Daozong also won a victory at Lingzhou. In 626（Wude 9）, after Tang counterattacks at Qinzhou and Jingyang, Duobi still brought his forces to the Wei River. The Alliance of Bian Qiao led to withdrawal and the return of some captives but did not create a lasting stable relationship.

Internal Rule and the Tribal Alliance

Duobi placed Tuli Khan in command of the eastern part of the khaganate and initially relied on the Ashina royal clan and the political network associated with Princess Yicheng and the Sui imperial house. After Tuli was defeated while campaigning against Xueyantuo, the Uyghurs, and other groups, Duobi detained and flogged him. Tuli then refused to provide troops and appealed to the Tang, making the khaganate's internal division public. Tang historical sources also record that Duobi gave Zhao Deyan major responsibility for government, entrusted some authority to non-Turkic groups, and imposed levies on subordinate peoples. Combined with years of warfare, these policies intensified tribal alienation after snow disasters and famine. From 627 to 629（Zhenguan 1–3）, Xueyantuo, the Uyghurs, Bayegu, and other groups successively rebelled or shifted allegiance, while Tuli and other leaders also left Duobi's control. The military and political support available to the Eastern Turkic Khaganate steadily diminished.

The Alliance of Bian Qiao and Treatment after Defeat

During the Wei River confrontation in 626（Wude 9）, Duobi attempted to exploit military pressure during the Tang transition between rulers. Emperor Taizong personally went to the Wei River and had the main army deploy behind him, prompting Duobi to shift from advance to negotiation. The negotiations at Iron Mountain in 630（Zhenguan 4） ended differently. The Tang court sent envoys to reassure Duobi, while Li Jing judged that he was preparing to flee north and attacked while his guard was relaxed, ultimately capturing him and breaking up his followers. Emperor Taizong did not execute Duobi but returned his family, gave him a Tang office, and provided a residence. The two negotiations show the contrast between Duobi's position when he was militarily strong and when the khaganate was collapsing.

An Outline of His Deeds

Ashina Duobi's deeds lie first in his raiding of the frontier: in the Wude years he repeatedly led his horsemen deep in, and once came to the north of the Bian bridge on the Wei River, where Taizong himself rode out to the Wei, spoke with him across the water and rebuked him for breaking his oath, so that Illig was shaken and asked for peace and withdrew, which was the covenant of the Bian bridge; afterwards he still plundered the prefectures of Dai and Shuo year after year. Second, in his holding of his people: inheriting the height of Turkish power he did not order his own government, his levies were harsh and heavy and his tribes fell away, and the Tiele peoples such as the Xueyantuo and the Huihe revolted one after another, so that the strength of the state shrank day by day. Third, in his defeat and fall: in the fourth year of Zhenguan Li Jing made a night raid with three thousand picked horsemen, and Illig fled to the Iron Mountain and sought to enter Tuyuhun, but was seized by Su Ni-shi and handed over, and the Eastern Turks perished, more than a hundred thousand of the Turkish tribes surrendering southward to Tang, whom Taizong settled in the bend of the Yellow River, whence came the title of the Heavenly Khan.

Personal Relations

• Ashina Rangan（Yami Qaghan）: father; Duobi was his third son.
• Shibi Qaghan: elder brother; Shibi's son Shibo'bi was later appointed Tuli Khan by Duobi.
• Chuluo Qaghan: elder brother and predecessor; Duobi succeeded him after his death.
• Princess Yicheng: wife of Chuluo Qaghan; after Chuluo's death, Duobi married her according to the Turkic levirate custom.
• Shibo'bi（Tuli Khan）: nephew and eastern junior khan; initially campaigned with Duobi but later broke with him after military defeat, detention, and punishment.
• Yang Shanjing: younger brother of Princess Yicheng; together with Wang Wensu, urged Duobi to install Yang Zhengdao as a Sui prince.
• Yang Zhengdao: Sui prince supported by Duobi as part of an effort to continue the political claim of the Sui imperial house.
• Yuan Junzhang: leader of the Mayi forces who joined Duobi in attacks on the Tang.
• Liu Heita: regional power in Hebei during the late Sui and early Tang; brought Turkic troops into Hebei.
• Emperor Gaozu of Tang Li Yuan: Tang emperor; during the early part of Duobi's reign responded to his military pressure with gifts and negotiations.
• Emperor Taizong of Tang Li Shimin: Tang emperor and principal opponent; concluded the Alliance of Bian Qiao with Duobi and later oversaw the defeat of the Eastern Turkic Khaganate and Duobi's treatment after capture.
• Zheng Yuanshu: Tang envoy who went to the Turks and urged Duobi to withdraw.
• Zhao Deyan: political adviser employed by Duobi; Tang historical sources record that his policies provoked dissatisfaction among the people.
• Li Jing: Tang commander who defeated Duobi's forces in the campaign that destroyed the Eastern Turkic Khaganate.
• Li Ji: Tang general who intercepted Duobi's defeated forces fleeing north at Qikou.
• Zhang Baoxiang: deputy Tang expedition commander who captured Duobi after his flight.
• Ashina Dieluoshi: Duobi's son; captured by Tang forces when the Eastern Turkic Khaganate collapsed.

Historical Assessment

Accounts in Tang-Period Historical Sources

The Old Book of Tang states that after Duobi's accession he "inherited the resources of his father and elder brothers, possessed strong troops and horses, and intended to dominate China." This is a Tang historian's summary of his early military position. Emperor Taizong of Tang's enumeration of five offenses after Duobi's capture was the victor's official statement concerning his political and military conduct; the same account also records that the Tang court chose to spare his life and settle him in Chang'an. These records reflect the evaluative standpoint of Tang sources and are not equivalent to a neutral first-person account.

Narratives in Later Historical Works

The New Book of Tang places the khaganate's internal divisions, tribal defections, natural disasters, and Duobi's warfare against the Tang together in its narrative of the collapse of the Eastern Turkic Khaganate. The Comprehensive Mirror in Aid of Governance gives more detailed accounts of the Bian Qiao negotiations, the break between Tuli and Duobi, and Li Jing's decision to attack at Iron Mountain. On the basis of these narratives, Duobi's defeat resulted both from Tang military action and from the loss of tribal support and shifts in external allegiance. This is a synthesis of the processes recorded in the sources rather than a direct quotation from a historian.