Xu Da led a pursuit on the retreating Yuan forces and encountered Taejo of Joseon, the founder of the Korean Joseon dynasty, who was ordered by the Mongols to attack the Ming army. Xu Da's presence struck fear into the Korean generals, who in turn, allied themselves with the Ming forces instead. Afterwards, Xu Da's army entered Mongol territory, routed Mongol reinforcements, sacked the Mongol capital at Karakorum, and captured thousands of Mongol nobles in 1370. His army ventured to Transbaikalia and reached further north than any other Chinese army had ever before.