quality:correction, quality:corruption
Rise of the Jurchens

In 1583, Nurhaci, the leader of one of the many Jurchen tribes in southern Manchuria, began to establish his own state. He united the Jurchens with the support of the Ming dynasty, particularly General Li Chengliang. However, some Ming officials grew concerned about Nurhaci's growing power and called for his destruction in 1587. However, this issue was not resolved due to discussions within the Ming administration. Nurhaci acknowledged his subordinate relationship to the Ming dynasty and paid tribute in 1590 and 1597 by personally visiting Beijing. By the early 1590s, Nurhaci's state had a large military force, estimated at 30–40,000 horsemen and 10,000 infantry. The Ming authorities declined his offer to lead his army into Korea against the Japanese. In 1599, as part of building his state, Nurhaci introduced a new Manchu script and in 1601, a new organization based on banners. In 1603, he reached an agreement with Ming generals in Liaodong to define the borders.

In 1618, Nurhaci had gained control over all the Jurchen tribes except for Yehe and Haixi, who were under Ming protection. An attack on these tribes would trigger a war with China, which is exactly what Nurhaci provoked by raiding Fushun in May 1618. The Ming retaliated with an expedition in early April 1619, after extensive and costly preparations. Yang Hao, a former commander in Liaodong and leader of the Ming forces in Korea from 1597–1598, was put in charge of the overall command. The army was divided into four corps, led by experienced generals (from north to south) Ma Lin, Du Song, Li Rubai, and Liu Ting. The Ming troops consisted of about 100,000 men, including 83,000 Chinese, with the rest being Korean and Jurchen allies. On the other hand, Nurhaci had 50–60,000 soldiers at his disposal, but unlike the Chinese, he did not divide them. Instead, he used his knowledge of the terrain, weather, and mobility to his advantage and crushed the individual Ming corps one by one. First, he defeated Du Song's corps on 14 April, followed by Ma Lin's the next day. Yang Hao, in response, ordered a retreat, and while Li Rubai attempted to retreat as well, the order did not reach Liu Ting and his corps, resulting in their defeat on 20 April. Generals Du Song and Liu Ting both fell in battle. After defeating the Ming, Nurhaci joined forces with the remaining Jurchens and occupied Kaiyuan, where he killed General Ma Lin, and Tieling in northern Liaodong. As a result of the defeat, Li Rubai was accused of cowardice and committed suicide under the weight of criticism, while Yang Hao was imprisoned and executed in 1629.