Korean–Jurchen border conflicts

The Korean–Jurchen border conflicts were a series of conflicts from the 10th century to the 17th century between the Korean states of Goryeo and Joseon and the Jurchen people.

Background
In 993, the land between the border of Liao and Goryeo was occupied by troublesome Jurchen tribes, but the Goryeo diplomat Sŏ Hŭi was able to negotiate with Liao and obtain that land up to the Yalu River, citing that in the past it belonged to Goguryeo, the predecessor to Goryeo.

Both Balhae remnants and miscellaneous tribal peoples like Jurchens lived in the area between the Yalu and Daedong rivers which was targeted for annexation by Goryeo.

Goryeo period
The Jurchens in the Yalu River region were tributaries of Goryeo since the reign of Wang Kŏn, who called upon them during the wars of the Later Three Kingdoms period, but the Jurchens switched allegiance between Liao and Goryeo multiple times, taking advantage of the tension between the two nations; posing a potential threat to Goryeo's border security, the Jurchens offered tribute to the Goryeo court, expecting lavish gifts in return, which was the custom of the sinospheric order at the time.

Joseon period
The Joseon Koreans tried to deal with the Jurchens by using both forceful means and incentives. Sometimes the military was dispatched, in tandem with appeasement with titles and degrees, and allowing Jurchens to sell furs for Joseon crops to make up for Jurchens' lack of food. Starting with Lee Ji-ran's recommendation and example, attempts were started to acculturate Jurchens by having Koreans marry them to integrate them into Korea. Despite the tributary relations and gifting and acculturating, many Jurchen tribes were submissive one year and rebellious the next. By the 1400s, the Ming Yongle Emperor was determined to wrest the Jurchens out of Korean influence and have China dominate them instead.

A key Jurchen leader named Mengtemu (Möngke Temür), chief of the Odoli Jurchens, who had always claimed he had been a servant of the Taejo of Joseon since Taejo's days as a border general of Goryeo, and even following him (Taejo Lee Seong-gye) to his wars, because he fed Mengtemu's family and provided land for him to live during his impoverished youth. Mengtemu was asked by Joseon to reject Ming's overtures, but was unsuccessful since Mengtemu folded and submitted to the Ming in 1412.

Joseon under Sejong the Great engaged in military campaigns against the Jurchen and after defeating the Odoli, Maolian and Udige clans, Joseon managed to take control of Hamgyong. This shaped the modern borders of Korea around 1450, when several border forts were established in the region.

Aftermath
Nurhaci, who was originally a vassalage to the Ming dynasty, made efforts to unify the Jurchen tribes including the Jianzhou, Haixi and Wild Jurchens. He offered the Ming dynasty to send Jianzhou Jurchen troops into Korea to fight against the Japanese forces during the Japanese invasions of Korea in the 1590s. The Ming dynasty was still fully recognized by Nurhaci as his overlord since he did not send this message to Joseon and only to the Ming. Nurhaci's offer to fight against the Japanese was denied due to misgivings from the Koreans, but the Ming awarded Nurhaci the title of dragon-tiger general (龍虎將軍) along with another Jurchen leader.

Nurhaci later established the Later Jin dynasty and openly renounced Ming overlordship with the Seven Grievances in 1618. A 30,000-strong Jurchen force led by Nurhaci's nephew Amin overran Joseon's defenses during the Later Jin invasion of Joseon in 1627. The Jurchens pushed Joseon to adopt "brotherly relations" with the Later Jin through a treaty. In 1636, Nurhaci's son and Qing emperor Hong Taiji dispatched a punitive expedition to Joseon because Injo of Joseon persisted in his anti-Jurchen (anti-Manchu) policies. Having been defeated, Joseon was compelled to sever ties with the Ming and instead recognized the Qing as suzerain according to the imperial Chinese tributary system.