Esen Taishi

Esen (Mongolian: Эсэн; Mongol script: ᠡᠰᠡᠨ; Chinese: 也先)[4] (1407–1454), was a powerful Oirat taishi and the de facto ruler of the Northern Yuan dynasty between 12 September 1453 and 1454.

He is best known for capturing the Emperor Yingzong of Ming in 1449 in the Battle of Tumu Fortress and briefly reuniting the Mongol tribes.

Esen was born to his father, Toghan, the Choros taishi who had expanded Oirat territory substantially, with more Mongol tribes acknowledging his supremacy.

Under Esen Taishi's leadership, the Mongols under Taisun Khan unified the North Yuan, including the Jurchens and Tuvans in Manchuria and Siberia.

In the 1430s, Esen also took over control of the Mongol kingdom known as Kara Del in the Hami oasis between the Gobi and the Takla Makan deserts.

The Ming dynasty had for some time pursued a "divide and rule" strategy in dealings with their northern neighbors, maintaining trade 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.

The Ming tried to stir rivalry between Taisun Khan, but Esen chose "rivals" below him in status to counter the divide and rule strategy.

Esen encouraged hundreds of Mongol, Hami, and Samarkand-based Muslim merchants to accompany his missions to the Ming Emperor.

Yu Qian (于謙), the defense minister of Ming, who was organizing the counterstrike, commented that the emperor's life is not as important as the fate of the country.

Since the Mongol economy relied on their trade with the Ming dynasty, Esen was obligated to reopen negotiations, now under a much weaker position.

Agbarjin jinong, who was married to Esen's daughter Tsetseg, was promised the new title of khan and deserted to the Oirats.

Taisun, supported by the Ming dynasty's Three Guards, openly led his own forces against Esen and Agbarjin in 1451, but they were outnumbered and the khan was eventually killed in 1452 while attempting to flee.

Tsetseg was pregnant at the time, and Esen promised to kill the baby if it was male, but Samur Gunj helped the infant prince escape when he was born.

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.

Other Oirat leaders joined the rebellion against Esen, and he was defeated in battle and murdered in 1454, a year after his assumption of the title of khan.

After his death, the Oirats no longer held sway over eastern Mongolia, which had come under their control through Esen and his father's influence.