Jajangmyeon (자장면) or jjajangmyeon (짜장면) is a Korean-style Chinese noodle dish topped with a thick sauce made of chunjang, diced pork, and vegetables. It originated in Incheon, Korea where Chinese migrant workers started making zhajiangmian (noodles served with fried bean sauce) in the late 19th century. Modifications in Korea such as a darker and sweeter sauce differentiate the Korean dish from the Chinese version.

Both the name and dish originate from the Chinese zhájiàngmiàn (炸酱面). The common features of both are pork, long wheat noodles, and a sauce made from fermented soybean paste. Originally the sauce that was introduced from China to make the noodle dish, had tasted saltier and was also of a brownish colour. The chefs at Incheon, Korea later added in caramel to sweeten it up as well as adding in grains, that darkened the sauce to looking jet black over time.

https://en.wikipedia.org/wiki/Jajangmyeon