Red Turban Rebellion
As Goryeo was a tributary, or "Bumaguk (son-in-law nation)", to the Mongol Yuan dynasty since 1259, Choe Yeong was sent to help the Yuan forces quash insurgents during the Red Turban Rebellion in northern China. In 1354, at the age of 39, he deployed to northern China with 2,000 Korean mounted archers, and was reinforced in Kanbaluk by 20,000 veterans of the Goryeo Tumens. Together they suppressed the Red Turban Rebellion and returned home to Goryeo. However, later the Yuan dynasty was overthrown by the uprisings of Zhu Yuanzhang, who founded the Ming dynasty, and Chen Youliang, who founded the Chen Han dynasty.