Early reign (626–633) One of the first actions that Emperor Taizong carried out as emperor was releasing a number of
ladies in waiting from the palace and returning them to their homes, so that they could be married. He made his wife Princess Zhangsun the empress, and their oldest son
Li Chengqian the crown prince. Emperor Taizong also immediately faced a crisis, as the
Eastern Turkic leader
Illig Qaghan (Ashina Duobi), along with his nephew the subordinate Tuli Khan
Ashina Shibobi (), launched a major incursion toward Chang'an, and just 19 days after Emperor Taizong took the throne, the two khans were just across the
Wei River from Chang'an. Emperor Taizong, accompanied by
Gao Shilian and
Fang Xuanling, was forced to meet Ashina Duobi across the river and personally negotiate peace terms, including tributes to
Eastern Turks, before Ashina Duobi withdrew. Late in 626, Emperor Taizong ranked the contributors to Tang rule and granted them titles and fiefs, naming among the first rank of contributors
Zhangsun Wuji,
Fang Xuanling,
Du Ruhui,
Yuchi Jingde, and
Hou Junji. When Li Shentong, as his distant uncle, objected to being ranked under Fang and Du, Emperor Taizong personally explained how Fang and Du's strategies allowed him to be successful, and this managed to get the other objectors to quiet down, as Emperor Taizong was even willing to rank low such an honored individual as Li Shentong. Emperor Taizong also buried Li Jiancheng and Li Yuanji with honors due imperial princes and had their staff members attend the funeral processions. Meanwhile, he appeared to begin to reshuffle government further—which he had already begun after being created crown prince—by dismissing his father's trusted advisors
Xiao Yu and
Chen Shuda, making his own trusted advisors chancellors. (Xiao, however, was soon restored to being chancellor, although his career during Emperor Taizong's reign would see repeated dismissals and repeated restorations.) However, he also began to greatly pay attention to the officials' submissions and their criticism of imperial governance, making changes where he saw needed. He also particularly began to trust
Wei Zheng, accepting much advice from Wei as far as his personal conduct was concerned. He was also willing to demote his own trusted advisors, as he demoted
Gao Shilian after finding that Gao had held back submissions from his deputy Wang Gui. Viewing Sui's Emperor Yang as a negative example, he frequently solicited criticism, rewarding those officials willing to offer them, particularly Wei and Wang Gui. His openness to opposing ideas was also evident in his attempt to reconcile traditional
Taoist religion and
Buddhism, as demonstrated in his ''Emperor's Preface to the Sacred Teachings'' (), and Emperor Taizong was at least a nominal Taoist.
Li Yi's Rebellion Also in 627, the general
Li Yi the Prince of Yan—a late-Sui warlord who later submitted to Tang, who associated with Li Jiancheng—fearing that Emperor Taizong would eventually take action against him, rebelled at Bin Prefecture (, in modern Xianyang), but was quickly crushed by the official Yang Ji () and killed in flight. Later that year, when Emperor Gaozu's cousin Li Youliang () the Prince of Changle, the commandant at Liang Prefecture (, roughly modern
Wuwei, Gansu), was accused of allowing his staff to oppress the people and to trade with
Qiang and
Xiongnu tribesmen, Emperor Taizong sent the chancellor
Yuwen Shiji (Yuwen Huaji's brother) to investigate, and in fear, Li Youliang's staff members plotted to hold him hostage and rebel. When this was discovered, Emperor Taizong forced Li Youliang to commit suicide. Late in the year, Wang Junkuo (), the commandant at You Prefecture (, roughly modern Beijing), also rebelled, but was defeated quickly and killed in flight. However, although there were also reports that Feng Ang (), a warlord in the
Lingnan region, was rebelling, Emperor Taizong, at Wei's suggestion, sent messengers to comfort Feng, and Feng submitted. Also in 627, Emperor Taizong, seeing that there were too many prefectures and counties, consolidated and merged many of them, and further created another level of local political organization above prefectures—the circuit ()—dividing his state into 10 circuits.
Campaign against the Eastern Turks , the ambassador of the
Tibetan Empire, in a
later copy of a painting by court artist
Yan Liben (600–673 CE) In 628, with Ashina Duobi and Ashina Shibobi having a falling out, Ashina Shibobi submitted to Emperor Taizong, as did the chieftains of
Khitan tribes, who had previously submitted to the
Eastern Turks. With their khaganate in turmoil, Ashina Duobi was no longer able to protect the last late-Sui rebel ruler who alone remained standing against Tang pressure—
Liang Shidu the Emperor of Liang, and in summer 628, with the Tang generals
Chai Shao and
Xue Wanjun () sieging the Liang capital
Shuofang (in modern
Yulin, Shaanxi), Liang Shidu's cousin Liang Luoren () killed Liang Shidu and surrendered, finally uniting China. With the
Eastern Turkic Khaganate weakened, their vassal
Xueyantuo also broke away and formed its own khanate, and Emperor Taizong entered into an alliance with Xueyantuo's leader Yinan, creating Yinan the Zhenzhupiqie Khan (or
Zhenzhu Khan in short). In late 629, believing the time ripe for a major attack on the
Eastern Turks, Emperor Taizong commissioned the general
Li Jing with overall command of a multi-pronged army, assisted by the generals
Li Shiji,
Li Daozong, Chai Shao, Xue Wanche (, Xue Wanjun's brother) and
Su Dingfang, attacking the
Eastern Turks at multiple points. The army was successful in its attacks, forcing Ashina Duobi to flee, and by late spring 630, Ashina Duobi had been captured, and
Eastern-Turkic chieftains all submitted to Tang. Emperor Taizong spared Ashina Duobi but detained him at Chang'an, and he considered what to do with the
Eastern Turks. The main opposing views were from the chancellors
Wen Yanbo (who advocated leaving the Turks within China's borders to serve as a defense perimeter) and Wei (who advocated leaving them outside the borders). Emperor Taizong accepted Wen's suggestion and established a number of prefectures to accommodate the Turks, leaving them governed by their chieftains without creating a new khan to govern them. In 631, Emperor Taizong established a
feudal scheme, where the contributors to his reign were given, in addition to their current posts, additional posts as prefectural governors, to be passed on to their descendants. Soon, however, receiving much opposition to the plan, the strongest of which came from
Zhangsun Wuji, Emperor Taizong cancelled the scheme. After the conquest of the
Eastern Turkic Khaganate, Emperor Taizong's officials repeatedly requested that he carry out sacrifices to heaven and earth at
Mount Tai, and Emperor Taizong, while at times tempted by the proposal, was repeatedly dissuaded from doing so by Wei, who pointed out the expenses and the labors that would be imposed on the people as a result, and also that this would open China's borders to attack.
Middle reign (634–641) In 634, Emperor Taizong sent 13 high level officials, including
Li Jing and
Xiao Yu, to examine the circuits to see whether the local officials were capable, to find out whether the people were suffering, to comfort the poor, and to select capable people to serve in civil service. (Li Jing initially recommended
Wei Zheng, but Emperor Taizong declined sending Wei, stating that Wei needed to stay to point out his faults and that he could not afford to have Wei away even for a single day.)
Campaign against Tuyuhun Around this time, Tang was having increasing conflicts with
Tuyuhun, whose Busabo Khan
Murong Fuyun, under instigation by his strategist the Prince of Tianzhu, had been repeatedly attacking Tang prefectures on the borders. At one point,
Murong Fuyun sought to have a Tang princess marry his son the Prince of Zun, but the marriage negotiations broke down over Emperor Taizong's insistence that the Prince of Zun come to Chang'an for the wedding. In summer 634, Emperor Taizong had the generals
Duan Zhixuan and Fan Xing () lead forces against Tuyuhun, but with Tuyuhun's forces highly mobile and avoiding direct confrontation, Duan, while not defeated, could not make major gains. Once Duan withdrew, Tuyuhun resumed hostilities. In winter 634, with the
Tibetan king
Songtsän Gampo making overtures to marry a Tang princess as well, Emperor Taizong sent the emissary Feng Dexia () to Tibet with an eye toward an alliance against Tuyuhun. In winter 634, he commissioned
Li Jing, assisted by the other generals
Hou Junji,
Xue Wanjun,
Xue Wanche,
Qibi Heli,
Li Daozong,
Li Daliang, Li Daoyan (), and
Gao Zengsheng (), to attack Tuyuhun. In 635, Li Jing's forces crushed Tuyuhun forces. Murong Fuyun was killed by his own subordinates, and his son
Murong Shun killed the Prince of Tianzhu and surrendered. Emperor Taizong created Murong Shun the new khan, although Murong Shun was soon assassinated. Emperor Taizong then created Murong Shun's son
Murong Nuohebo as the new khan. In 635, Emperor Gaozu died, and Emperor Taizong, observing a mourning period, briefly had Li Chengqian serve as regent, and after he resumed his authorities less than two months later, he still authorized Li Chengqian to thereafter rule on minor matters. In spring 636, Emperor Taizong commissioned his brothers and sons as commandants and changed their titles in accordance with the commands that they received, sending them to their posts—with the exception of his son
Li Tai the Prince of Wei, who by this point was beginning to be highly favored by him. He further allowed Li Tai to engage literary men to serve as his assistants, as Li Tai favored literature. From this point on, Li Tai would be so favored that there began to be talks that Emperor Taizong might let him displace Li Chengqian, whose favors began to wane. In fall 636,
Empress Zhangsun died. Emperor Taizong mourned her bitterly and personally wrote the text of her monument. In the summer of 637, Emperor Taizong recreated the feudal scheme that he had considered and abandoned in 631, creating 35 hereditary prefect posts. (By 639, however, the system was again abandoned after much opposition.)
Treatment of Noble Clans of Emperor Taizong on a Tang stele. Sometime before 638, Emperor Taizong, disgusted with the traditional noble clans of Cui, Lu, Li, and Zheng and believing that they were abusing their highly honored names, commissioned
Gao Shilian, Wei Ting,
Linghu Defen, and
Cen Wenben to compile a work later to be known as the
Records of Clans (), with the intent of dividing the clans into nine classes based on their past contributions, good deeds, and ill deeds. In an initial draft that Gao submitted, he nevertheless ranked the branch of the Cui clan that the official Cui Min'gan () belonged to as the highest, a decision that Emperor Taizong rebuked, as he pointed out that Gao was merely again looking at tradition and not the recent contributions. He therefore personally intervened in revising the work, reducing Cui's clan to the third class.
Tibetan attack on Songzhou In fall 638, Tibet's Songtsän Gampo, displeased that Emperor Taizong had declined to give him a Tang princess in marriage and believing that Murong Nuohebo had persuaded Emperor Taizong to decline the marriage proposal, launched a major attack with forces of 200,000 on Tuyuhun and then on several Tang prefectures, putting Song Prefecture (, roughly modern
Ngawa Tibetan and Qiang Autonomous Prefecture, Sichuan) under siege. Emperor Taizong commissioned
Hou Junji, assisted by
Zhishi Sili (), Niu Jinda (), and Liu Jian (), of a total of force of 50,000 to counterattack, and Niu, who commanded the forward forces, defeated Tibetan forces at Song Prefecture. Songsän Gampo withdrew and sued for peace but still sought to marry a Tang princess. Emperor Taizong agreed this time. Also in 638, believing that
Xueyantuo was growing increasingly strong and difficult to control, Emperor Taizong granted Yinan's sons
Bazhuo and Jialibi () both lesser khan titles, to try to create dissensions between them. In summer 639,
Ashina Jiesheshuai (), the younger brother of Ashina Shibobi, whom Emperor Taizong did not favor and gave little recognition to, formed a conspiracy with Ashina Shibobi's son Ashina Hexiangu () to assassinate Emperor Taizong. They had planned to wait for
Li Zhi the Prince of Jin to depart from the palace in the morning and use that opportunity to attack the palace. On the day they planned, however, Li Zhi did not leave the palace, and Ashina Jiesheshuai attacked anyway but was quickly defeated, captured, and executed. After this incident, however, the officials began advocating sending the Turks away from the heart of the state. In fall 639, Emperor Taizong created a Turkish prince who had served him faithfully, Li Simo (né Ashina Simo) as the khan of a newly recreated
Eastern Turkic state (as
Qilibi Khan), giving him all of the Turks and
Xiongnu who had surrendered as his subordinates, to be settled north of the
Great Wall and the Yellow River. However, the Turks were fearful of Xueyantuo and initially refused to head to their new location. Emperor Taizong issued an edict to Yinan that he and Li Simo keep their peace and not attack each other, and after receiving from Yinan the assurance that he would not attack, the Turks advanced to the new location.
Campaign against Western Turks Taizong began a
series of campaigns against the
Western Turks (
Xitujue) and their allies, the oasis states of the
Tarim Basin, around 640. These hostilities between the
Western Turks and Tang would continue until the defeat and
conquest of the Western Turks in 657 under Taizong's successor, Gaozong. The kingdoms of
Shule and
Khotan surrendered to the Chinese in 632, as did the kingdom of
Yarkand in 635.
King Yeongnyu, the king of Goguryeo, was apprehensive about his general
Yŏn Kaesomun and was plotting with his other officials to kill Yeon. When Yŏn received the news, he started a coup and killed the king and the high-level officials. He declared King Yeongnyu's nephew Ko Chang (
King Bojang) king, while taking power himself with the title of
Dae Mangniji (,
Generalissimo). When Emperor Taizong received the news, there were suggestions that an attack be launched against Goguryeo, suggestions that Emperor Taizong initially declined. In spring 643, Wei died, and Emperor Taizong mourned him bitterly, authoring Wei's monument himself and, prior to Wei's death, promising to give his daughter Princess Hengshan in marriage to Wei's son Wei Shuyu (). Later in spring, Emperor Taizong commissioned 24
portraits at Lingyan Pavilion to commemorate the 24 great contributors to his reign.
Contacts with the Byzantine Empire , Emperor Taizong recognized the
Nestorian Church of the East, due to efforts of the Christian missionary
Alopen in 635 CE. The
Old Book of Tang and
New Book of Tang mention
several embassies made by Fu lin (; i.e. the
Byzantine Empire), which they equated with
Daqin (which may refer to the
Roman Empire or Middle East), beginning in 643 with an embassy sent by the king
Boduoli (, i.e.
Constans II Pogonatos) to Emperor Taizong, bearing gifts such as
red glass and green
gemstones. These histories also provided cursory descriptions of
Constantinople and
its walls, as well as
how it was besieged by
Da shi (; the Arabs of the
Umayyad Caliphate) and their commander "Mo-yi" (; i.e.
Muawiyah I, governor of Syria before becoming
caliph), who forced the Byzantines to pay tribute.
Henry Yule highlights the fact that
Yazdegerd III (r. 632–651), last ruler of the
Sasanian Empire, sent diplomats to China for securing aid from Emperor Taizong (
considered the suzerain over
Ferghana in Central Asia) during the loss of the
Persian heartland to the Islamic
Rashidun Caliphate, which may have also prompted the Byzantines to send envoys to China amid their
recent loss of Syria to the Muslims. Tang Chinese sources also recorded how Sassanid prince
Peroz III (636–679) fled to Tang China following the
conquest of Persia by the growing Islamic caliphate. The expansion of China's power into Central Asia under Emperor Taizong seems to have been noticed in the West.
Theophylact Simocatta, a
Byzantine Greek historian during the reign of
Heraclius (r. 610–641), wrote that
Taugast (or
Taugas;
Old Turkic:
Tabghach, from
Tuoba, the
Xianbei clan of
Northern Wei), was a great eastern empire in the Far East that ruled over
Turkic people, with a capital city roughly 1,500 miles northeast from India that he called
Khubdan (from the Turkic word
Khumdan, meaning,
Chang'an), where
idolatry was practiced but the people were wise and lived by just laws. He depicted the Chinese empire as being divided by a great river (i.e. the
Yangzi) that served as the boundary between
two rival states at war, yet during the reign of Byzantine Emperor
Maurice (582–602 CE) the northerners wearing "black coats" conquered the "red coats" of the south (black being a distinctive color worn by the people of
Shaanxi, location of the Sui capital Sui Chang'an, according to the 16th-century Persian traveler Hajji Mahomed, or Chaggi Memet). This account may correspond to the conquest of the
Chen dynasty and reunification of China by
Emperor Wen of Sui (r. 581–604).
Succession dispute In 643, Emperor Taizong would see major turmoil among his own closest family. His son Li You () the Prince of Qi, angry over restrictions that his secretary general Quan Wanji () often placed on him, killed Quan and declared a rebellion. Emperor Taizong sent Li Shiji against Li You, but before Li Shiji could engage Li You, Li You was captured by his own subordinate Du Xingmin () and delivered to Chang'an, where Emperor Taizong ordered him to commit suicide and executed 44 of his associates. The death of Li You drew out news of another plot. Li Chengqian, who had been fearful that Emperor Taizong would eventually remove him and replace him with Li Tai, had begun to conspire with
Hou Junji, Li Yuanchang () the Prince of Han (Emperor Taizong's brother), the general Li Anyan (), and his brothers-in-law Zhao Jie () and Du He (, Du Ruhui's son) to overthrow Emperor Taizong. During the investigations in the aftermaths of Li You's rebellion, one of the co-conspirators, Li Chengqian's guard Gegan Chengji (), was implicated by association, and in order to save himself, he revealed Li Chengqian's plot. Emperor Taizong was shocked by the news, and he appointed
Zhangsun Wuji,
Fang Xuanling,
Xiao Yu, and
Li Shiji, along with the officials in charge of the supreme court and the legislative and examination bureaus of the government to carry out a joint investigation. At the suggestion of the mid-level official
Lai Ji, Emperor Taizong deposed, but did not kill, Li Chengqian, while ordering Li Yuanchang to commit suicide and executing Hou Junji, Li Anyan, Zhao, and Du. Li Chengqian chose to speak Turkic, dress in Turkic clothes and even set up a tent in his residence in imitation of a Turkic khan. Taizong removed him from the position of heir apparent and chose as his successor Li Zhi, who embraced Han Chinese cultural heritage. After Li Chengqian was deposed, Emperor Taizong briefly promised Li Tai that he would be made crown prince. However, as the investigations continued, Emperor Taizong came to the belief that Li Chengqian's downfall was driven by Li Tai's machinations and therefore resolved to depose Li Tai as well. At Zhangsun's suggestion, Emperor Taizong had a younger son,
Li Zhi the Prince of Jin (who, like Li Chengqian and Li Tai, were born of
Empress Zhangsun), made the crown prince, who was considered kinder and gentler, while exiling Li Chengqian and Li Tai. However, starting later that year, Emperor Taizong began to doubt whether Li Zhi's personality was sufficiently strong to serve as emperor, and he toyed with the idea of making another son,
Li Ke the Prince of Wu, a son of his concubine Consort Yang (Emperor Yang of Sui's daughter), crown prince, but did not do so due to strong opposition by Zhangsun Wuji. Meanwhile, coming to the belief that he made an ill-advised promise to Yinan to give him Princess Xinxing in marriage, Emperor Taizong demanded a large amount of
bride price – 50,000 horses, 10,000 cows and camels, and 100,000 sheep—a price that Yinan agreed to, but could not immediately collect and deliver. Emperor Taizong used it as an excuse to cancel the marriage agreement. Meanwhile, as
Wei Zheng had, prior to his death, recommended Hou Junji and Li Chengqian's staff member
Du Zhenglun as chancellors, Emperor Taizong came to suspect that Wei was part of the plot as well. He destroyed the monument he had authored for Wei and cancelled the betrothal between Wei Shuyu and Princess Hengshan.
Campaign against the Karasahr In 644, with
Yanqi's king Long Tuqizhi (), who had assisted the Tang campaign to conquer Gaochang, turning against Tang and allying with the
Western Turks, Emperor Taizong sent the general Guo Xiaoke (), the commandant at Anxi (, i.e., Gaochang) to launch a
surprise attack on Yanqi. Guo caught Long Tuqizhi by surprise and captured him, making his brother Long Lipozhun () regent. (The
Western Turkic viceroy Ashina Quli () subsequently captured Long Lipozhun and briefly occupied Yanqi, although he then, not wanting a direct confrontation with Tang, withdrew, and the Yanqi nobles made Long Tuqizhi's cousin Long Xuepoanazhi () king.)
Goguryeo-Tang War tried to invade
Goguryeo in 598, 612, 613 and 614. Taizong campaign (map) was in 645. Gaozong's campaigns were in 661, 667 and 668. Also in 644, with Goguryeo attacking
Silla and Silla requesting aid, Emperor Taizong decided to prepare for a campaign to conquer Goguryeo. He arrested the emissaries that Yŏn sent to the Tang court, accusing them of disloyalty to King Yeongnyu. By winter 644, the mobilization was in full force. (Apparently because of Tang's preparation to attack Goguryeo, however, the reconstituted
Eastern Turkic people, fearing an attack from Xueyantuo at a time that Tang would be ill-equipped to assist, panicked and abandoned their khan
Li Simo, fleeing into Tang territory. Emperor Taizong reabsorbed the
Eastern Turks into Tang, while making Li Simo a general in his army.) In spring 645, Emperor Taizong departed from Luoyang and led the troops northeast, behind a vanguard of 60,000 commanded by
Li Shiji and
Li Daozong. At the same time, Zhang Liang led the other 40,000 from sea. By summer 645, Tang forces had captured
Yodong Fortress (, in modern
Liaoyang, Liaoning) and headed southeast toward the Goguryeo capital
Pyongyang. Emperor Taizong personally led about 30,000 Tang and tribal forces and defeated a 150,000-force commanded by two Gogureyo generals and then put Ansi (, in modern
Anshan, Liaoning) fortress under
siege. However, the capable defense put up by Ansi's commanding general stymied Tang forces and, in late fall, after suffering some casualties, with winter fast approaching and his food supplies running out, Emperor Taizong withdrew. He much regretted launching the campaign and made the comment, "If
Wei Zheng were still alive, he would never have let me launch this
campaign." He re-erected the monument he authored for Wei and summoned Wei's wife and children to meet him, treating them well.
Campaign against Xueyantuo and conquest of the Kucha Meanwhile, in the aftermaths of the
Goguryeo campaign,
Xueyantuo's
Duomi Khan Bazhuo (son of Yinan, who had died earlier in 645) launched attacks against Tang's border prefectures, with largely inconclusive results. In spring 646, the Tang generals Qiao Shiwang () and Zhishi Sili counterattacked, defeating Bazhuo's forces, causing him to flee. His vassals
Huige, Pugu (), and Tongluo () tribes took the opportunity to rebel and attack him. Hearing this, Emperor Taizong launched a major attack, commanded by
Li Daozong,
Ashina She'er (), Zhishi Sili, Qibi Heli, Xue Wanche, and Zhang Jian, against Xueyantuo. With Xueyantuo under attack from multiple sides, Bazhuo was killed by
Huige forces, and the remaining Xueyantuo people fled and supported Bazhuo's cousin Duomozhi as
Yitewushi Khan but soon offered to submit to Tang. Emperor Taizong sent
Li Shiji toward Duomozhi's location, with the direction to either accept his submission or destroy him. Duomozhi surrendered and was taken to Chang'an, ending Xueyantuo's rule over the region. The other tribes formerly submissive to Xueyantuo offered Emperor Taizong the title of "Heavenly Khan" and thereafter largely became submissive to Tang. Tang nominally established seven command posts and six prefectures over the region. (Huige's khan Yaoluoge Tumidu (), while submissive to Tang, for some time tried to take control over the region himself, but was subsequently assassinated in 648, and there would be no other organized attempt by Huige to take over the region until for about another century.) of a soldier and horse with elaborate
saddle and
stirrups, from the tomb of Emperor Taizong, c. 650. The relief shown here depicts "
Autumn Dew", also known as "Whirlwind Victory", and is housed at the Penn Museum in Philadelphia, Pennsylvania. After the victory over Xueyantuo, Emperor Taizong again turned his attention toward to Goguryeo, cutting off relations once more and considering another campaign. Under suggestions by some of his officials, he decided to launch harassment campaigns against Goguryeo's northern region on a yearly basis, to weaken Goguryeo gradually. The first of these campaigns was launched in spring 647, with
Li Shiji and Niu Jinda in command and would reoccur. All this was in preparation of another campaign in 649 with forces totaling 300,000, but Taizong died before this campaign and the campaign was stalled into Gaozong's reign. In 648, Emperor Taizong
launched another campaign, commanded by Ashina She'er, aimed at
Qiuzi, but first attacking Yanqi and killing Long Xuepoanazhi and replacing him with his cousin Long Xiannazhun (). Ashina She'er advanced on Qiuzi and captured its king Bai Helibushibi (), making his brother king instead. ==Death==