Esen Taishi

Esen (; Mongol script: ; ) (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 1450 in the Battle of Tumu Fortress and briefly reuniting the Mongol tribes. The Four Oirat reached the peak of their power under his rule. Name Esen means "good health" in Mongolian. Taishi is derived from the Chinese title 太師 (tàishī), meaning Grand Preceptor. Among Mongol tribes, this title was used for powerful nobles who were not part of the Chinggisid lineage. In Chinese, Esen is rendered as 也先 (Yěxiān) or less commonly as 額森 (Ésēn). Youth and early career