Think it is referring to the https://en.wikipedia.org/wiki/Imjin_War a series of two Japanese invasions of Korea: an initial invasion in 1592 also individually called the "Imjin War", a brief truce in 1596, and a second invasion in 1597 called the Chŏngyu War (정유재란; 丁酉再亂). The conflict ended in 1598 with the withdrawal of Japanese forces

Over the course of the war, the Ming sent in total 166,700 troops,[15] though Ming troops in Korea never numbered more than 60,000 at any given point.[115] They also sent 17 million liang worth of silver and supplies to Korea (equivalent to about half a year of revenue for the Ming Empire).

Chinese support is why korea even retain sovereignty, a point that most korea actively deny. Since it undermines Korean nationalism narratives, many Koreans suggest that the war never happened and that everything about the event is fabricated. This is a common historical revisionism tactic used in Korea to deny the Chinese influence that laid the foundation for much of what Koreans claim to be their original culture; rather blatant act of culture appropriation within korea nationalism movement.