Esen taishi

Esen taishi (Эсэн тайш; died 1455) was a powerful Oirat Khagan of the Northern Yuan Dynasty in Mongolia in the 15th century. He is best known for capturing the Zhengtong Emperor of the Ming Dynasty in 1450 after the Battle of Tumu Fortress and briefly reuniting the Mongols. The Western Mongols reached their peak under his rule.

Youth and early career
Esen was born to his father, Toghon, the Choros taishi (grand preceptor, from 太師) who had expanded Oirat territory substantially, with more Mongol tribes acknowledging his supremacy.

His early campaigns were against the Chaghatayid khans of Moghulistan. Esen three times defeated and twice captured the Moghuli ruler Uvais (Ways Khan) (1418–1432). Esen released him respecting his Chinggisid blood in both cases. The second time Uvais granted Esen his sister Makhtum Khanim who bore his two sons. Esen had to nominally convert to Islam in order to marry the Muslim princess, but remained effectively a shamanist.

After his father died in 1438, Esen inherited his position, taishi, for the reigning khan Togtoo-Bukha (r.1433-52). Under Esen taishi's leadership, the western Mongols and other Mongol tribes who support Togtoo-Bukha conquered the rest of Mongolia, and received the submission of the Jurchens and the Tuvans (Uriankhais) in Manchuria and Eastern Siberia. It is unarguably true that the Oirat warriors played a crucial role in this conquest. In the 1430s Esen also took over control of the Mongol kingdom called Qara Del in Hami oasis on the Silk Road between the Gobi and the Takla Makan deserts; after 1443-45 his conquest reached the northern border of Korea.

Conflict with the Ming
Esen's policy irritated or threatened the Chinese Ming Dynasty. The Ming had for some time pursued a "divide and rule" strategy in dealings with their northern neighbors, maintaining trade and tribute relationships, functioning as a kind of state-subsidized monopoly, with multiple leaders who they could then turn against one another by inciting jealousy or suggesting intrigue. A unified Mongolia under one ruler was, however, much less susceptible to such tactics. Also, many of the tribes brought under Oirat dominion by conquest either had inhabited areas claimed by China already, and other tribes had been pushed south into Chinese territory seeking to escape Oirat subjugation. The Chagatayid Hami oasis, furthermore, had paid tribute to the emperor before Esen convinced its ruler that bounty should go to the Oirat instead. Throughout the 1440s, Esen increased both the frequency of tribute missions to China and the number of representatives sent on each mission, meaning that the Chinese were obliged to provide ever-more expensive hospitality to the Mongols, irrespective of the actual trade or tribute being negotiated, and, according to surviving Chinese accounts, the Oirat demanded more and more lucrative tribute and trade agreements further skewed in the Mongols' favor.

One Chinese tactic for dealing with the situation, provoking rivalry between Mongol leaders, failed completely as they underestimated the degree of power Esen wielded and chose "rivals" too far below him in status for the strategy to be effective, including the figurehead Khan Togtoo Bukha. In addition, their other main tactic, meeting each demand for increased tribute or trade value with a decrease, backfired as well.

Esen encouraged hundreds of Mongol, Hami, and Samarkand based Muslim merchants to accompany his missions to the Ming Emperor. Since 1439 the Emperor Togtoo Bukha and Esen had been sending envoys to China, often numbering more than 1,000. In response to this inflation of numbers, the Zhengtong Emperor (1427–64) decreased the gifts to Esen and Togtaa-Bukha Khaan and closed border-trade with the Mongols.

Invasion of Ming China
In retaliation for real and perceived slights, Esen Tayisi led an Oirat invasion of northern China in 1449 which culminated in the capture of the Zhengtong Emperor at Tumu. The large-scale, three-pronged invasion began in July, with Khan Togtoo-Bukha leading the easternmost force to Liaodong, the grand councillor Alag attacking Xuanfu, and Esen himself heading the troops that sacked the city of Datong in August. Another column of the Mongols invaded Ganzhou. Acting on extremely poor advice from one of his advisors, the emperor also chose to lead his own armies into battle, with disastrous consequences.

Initial Chinese failures
The campaign was a series of routs and massacres of Chinese forces at Oirat hands, even though the imperial troops in the region are estimated to have numbered as many as 500,000 and Esen Tayisi had brought only 20,000 cavalry, expecting mainly to engage in traditional Oirat border raiding. Datong lay north of the Great Wall of China, and thus beyond its protection. After the initial attack on Datong, Esen feinted back to the Mongolian steppes. The emperor and his hastily-raised army chased the invaders west and met an ambush upon arriving at Datong. The Oirat horsemen harried the Chinese retreat back towards the wall for four days, through terrific thunderstorms, until the imperial army reached Tumu Bao (often translated Tumu Fortress). But rather than having secured a defensible position, the Chinese were trapped against the north side of Tumu, and Esen annihilated the Chinese army sent against him.

Capture of the Ming emperor
Most of the remaining soldiers, as well as all officers and courtiers of rank except the emperor himself, were slaughtered. Esen was still some distance away, near Xianfu. Six weeks later, when the captured emperor was brought to his camp and he had brought a more substantial force to the vicinity of Beijing, Esen attempted to ransom the emperor back to the Chinese. According to some accounts, it was at this point that Esen was granted the title "Tayisi".

In any case, the Chinese refused to negotiate a ransom, perhaps in part because the emperor's brother (a prince variously referred to as Zhu Qiyu, later the Jingtai Emperor) was by then installed on the throne and not eager to give up his new position. Yu Qian, the defence minister of Ming, who was organizing Chinese resistance, commented that the emperor's life is not as important as the fate of the country; he also believed that ransoming the emperor might boost the Mongols' morale and reduce that of the Ming.

Laying siege to Beijing
His ransom demand rebuffed, whether because the Chinese were calling Esen's bluff, believing he would consider the emperor more valuable alive than dead even without the possibility of ransom, or because the acting emperor was content not to obtain his brother's freedom, Esen began laying siege to the city. Esen offered the Emperor his sister in marriage, but the Emperor refused. The disheartened garrison in Beijing was under the command of the new commander Yu Qian who soon turned this unfavourable situation into a positive one. Not only did he use Beijing's fortifications to his advantage, but he also deployed various schemes to destroy the morale of the Mongol army. At one point, he ordered his forces to pretend that they had lost control of the city gate in order to lure a large force of Mongol riders into the city. Once a portion of the Mongol force was inside, the gate was shut and the Mongols were ambushed. Esen's sworn brother (anda) was killed in the attack. Having failed to take the city, Esen was soon forced to retreat under pressure from his own troops and by the arrival of reinforcements from elsewhere in China.

Negotiations
The Ming court elevated the Jingtai Emperor (r.1449-57) to the throne. Esen sent the captured emperor back in 1450. Since the Mongols relied on their trade-and-tribute relationship with China, Esen was then obligated to reopen negotiations from a much weakened position. While Sino-Mongol trade did not cease entirely during the Tumu Crisis, as the incident has come to be called, Esen had not only failed to win better terms than the prior arrangements, he was forced to accept less favorable terms in return for resumption of more normal relations with the Ming Empire. But Esen and Togtoo-Bukha again invaded the north of China, devastating the area around the confluence of the Nen and Songhua rivers.

Reign and death
Although, Togtoo-Bukha opposed Esen's policy of confrontation with the Ming, there was not any serious tension between the two. They quarreled over the designation of the heir of the throne. Esen wanted a son of his sister who was the wife of the khagan to be the successor of Togtaa-Bukha. But Togtoo-Bukha nominated his another son of the eastern Mongolian khatun as his heir instead. Togtoo-Bukha supported the Three guards and led his own forces openly against Esen in 1451; but they were outnumbered by Oirat loyalists and the nominal Khan was caught and killed by eastern tribesmen as he attempted to retreat. Togtaa-Bukha's brother Agbarjin jinong (viceroy), who married Esen's daughter Tsetseg, deserted to the Oirats and was promised the title of khagan of the Northern Yuan Dynasty. However, Esen murdered him after he invited Agbarjin with his male relatives at the feast. Esen attempted to kill the baby son of her daughter by Agbarjin' son, Qara Qurtsaq, but she and Esen's grandmother, Samur, hid the infant prince, Batu-Mongke, who would be a direct ancestor of Dayan Khan. Within eighteen months of his defeat of the titular Khan Toghto-Bukha, in 1453, Esen himself took the title of Great Khan of the Great Yuan (大元天盛可汗). At the same time the Oirats began an expedition into Moghulistan, Tashkent, Transoxiana

The Ming emperor was among the first to acknowledge the new title, but the reaction of Esen's fellow Mongols, Oirat and otherwise, mostly ranged from disapproving to enraged. Though Esen's line was related to the royal line descended from Temüjin (Genghis Khan) through his grandmother Samur gunji (princess), it was unlikely that he would have been considered eligible for election as Khan, and in any case Esen ignored the usual selection process: rather than the title of khan falling automatically to the eldest eligible male of the line, as in primogeniture, Mongol leaders were traditionally chosen by means of the kurultai, an elective monarchy system, with the members of a lineage voting to choose the title's successor from among themselves. This dissatisfaction soon escalated into open revolt against Esen's leadership.

Esen gave his son Amasanj the title of taishi, an action that led his powerful general Alag, who had expected to receive the title himself, into rebellion. Notable Oirat leaders joined the rebellion against Esen who was defeated at the battle and murdered in 1455, the year following his assumption of the title of khan, by the son of a political opponent whom Esen had executed. After his death, the Oirat no longer held sway over the areas of Mongolia which had come under their control only under his rule, and remained divided among themselves for many years. The 17th and 18th century Zunghar rulers considered themselves to be descendants of Esen Taishi.