Ligdan Khan
The Ming Great Wall was strengthened and the period was characterized by repeated Ming raids into Northern Yuan territory and vice versa. During the transition from Ming to Qing, the Northern Yuan monarch Ligdan Khan allied with the Ming against the Qing dynasty until Ligdan was defeated by Qing forces and Inner Mongolia was conquered by the Qing. In 1644, the Ming dynasty was overthrown by peasant rebels under Li Zicheng, who established the short-lived Shun dynasty which would soon be defeated by the Qing dynasty. During the Qing rule from 1691, Inner Mongolia and Outer Mongolia were incorporated into the empire.