The Ming dynasty gave Borjigin princes (descended from Genghis Khan's brothers) command of the Taining Guard, one of the Three Guards established in 1389. In 1446-48 most of the guards fled in the wake of Esen Tayisi's invasions. However, the Fuyu Guard, another of the Three Guards, remained along the Nen and Onon rivers. Said to have been the descendants of Khasar, a brother of Genghis Khan, they became the direct ancestors of the Khorchin Mongols.
Adai Khan of the Khorchin challenged the power of the Four Oirats and the Ming court in the succession struggle of Northern Yuan dynasty. However, he was killed by them in Ejene in 1438 and his tribe was forced to flee southward. The Khorchin appeared again in Mongolian chronicles with the rise of Unebolad wang in the late 15th century. The Khorchins allied with Dayan Khan and defeated the Uriyangkhai at the battle of Dalan Terqin in 1510.
In 1624, Nurhaci received the submission of Khorchins who roamed east of Khingan mountains and west of the Sungari. They were the first Mongol tribe that submitted to Qing dynasty. The Khorchins were responsible for production of fermented mare's milk for Manchu emperors. The later emperors of the Manchu Qing dynasty rewarded the Khorchin nobles highly for this early loyalty. Notable Empresses of the Qing dynasty, such as Empress Xiaozhuangwen (1613–88) and Empress Xiaohuizhang (1641–1717), were the Khorchin-Borjigins. The Khorchins were further divided into two wings (north and south), each with three Banners.