[1] Meju is produced by pounding, kneading, and shaping cooked soybeans, and undergoes fermentation with Aspergillus oryzae and/or Bacillus subtilis.

[6] 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."

[7][8] Jangdoks (pots) used for soy sauce brewing are found in the mural paintings of Anak Tomb No.3 from the 4th century Goguryeo.

[12] The Treatise on Food and Money, a section from the History of Goryeo, recorded that ganjang and doenjang were included in the relief supplies in 1018, after a Khitan invasion, and in 1052, when a famine occurred.

[13][14] Joseon texts such as Concise Reference for Famine Relief and Revised and Augmented Farm Management contain the detailed procedures on how to make meju for good quality ganjang and doenjang.