Esen Taishi

Esen (Mongolian: Эсэн; Mongol script: ᠡᠰᠡᠨ; Chinese: 也先; died 1455) was an Oirattaishi and khagan of the Northern Yuan dynasty between 1453 and 1454.

Esen, the son of Toghon taishi, distinguished himself in wars against Moghulistan, twice capturing its khan. After his father's death in 1438, he became the de facto ruler of the Mongols, despite being formally subordinate to Taisun Khan of the Northern Yuan. During the 1440s, he seized Hami on the Silk Road, controlled Gansu's Mongol principalities, subdued the Uriankhai, and unified Mongolia.

His relations with Ming China were marked by restricted trade and rising tensions. The Ming limited exchanges to tribute, and in 1449, reduced the goods granted to Esen's envoys. This led to war, partly due to the Ming refusal to grant an imperial princess to Esen's son. In July 1449, Esen led a major invasion of China. Ming forces under Emperor Yingzong were decisively defeated at the Battle of Tumu Fortress, and the Emperor was captured. The Ming enthroned his brother, the Jingtai Emperor, and Esen was unable to capitalize on his victory, making peace in 1450 and releasing Yingzong.

In the early 1450s, Esen eliminated Taisun during a succession conflict, briefly installed and killed a puppet khan, and then proclaimed himself khan. His later designation of his son, Amasanj, as the taishi provoked a rebellion led by his subordinate Alag, in which Esen was defeated and soon killed.