Traditional earthen jars used for aging gochujang and kimchi
Onggi are Korean ethnic earthenware, which were extensively used as tableware as well as storage containers in Korea. It includes both unglazed earthenware fired near 600~700°C and pottery with a dark brown glaze that burnt over 1100°C.
The origin of onggi dates to approximately 4,000 to 5,000 BC. There were two types of earthenware: a patternless earthenware which is called Mumun pottery and a black and red earthenware. The former, a patternless earthenware, was made with lumps of clay including much fine sand; however, the predecessor of Goryeo celadon and Joseon white porcelain, a black/red earthenware, was being made with only lumps of clay.
The color of earthenware is determined by the iron contained in the mud and the way of burning the pottery. The present onggi shape dates from the Joseon era. There are many records about onggi in Sejong Sillok Jiriji (세종실록지리지, King Sejong's Treatise on Geography): "There are three kilns that make the yellow onggi in Chogye-gun and Jinju-mok, Gyeongsang Province" (Lee and Jeong, 16).