Book of Wei
The "Records of the Three Kingdoms", a Chinese historical text written and published in the 3rd century, mentions that "Goguryeo people are good at brewing fermented soy beans." in the section titled "Eastern foreigners", in the "Book of Wei". Jangdoks (pots) used for soy sauce brewing are found in the mural paintings of Anak Tomb No.3 from the 4th century Goguryeo.