and covered with stone slabs. Heated walls with a double flue system were found in a 4th-century palace building in Jilin Province. It had an 'L' shaped adobe bench with a double flue system. The structure is more complex than a single flue system and has functionality similar to a kang. Literary evidence from Li Daoyuan's Commentary on the Water Classic also gives evidence of heated floors during the Northern Wei Dynasty (386-534 AD), though this was not explicitly named a dikang: The kang may have evolved to its bed design due to ongoing cultural changes during the Northern and Southern Dynasties, as high furniture and chairs came to be prevalent over the earlier style of floor-sitting and low-lying furniture in Chinese culture. The earliest kang remains have been discovered at Ninghai, Heilongjiang Province, in the Longquanfu Palace (699-926) of Balhae origin. Culture Traditional Chinese Dwellings (Zhongguo chuantong minju) (a bilingual text) has a few line drawings of kangs. It says that the kang is used to cook meals and heat the room, making full use of the heat-retaining capacity of the loess [soil used to make adobe]. The kang produces radiant heat to indirectly warm the interior space as well as the bed mass itself. It has been speculated that one of the oldest forms of Chinese housing, heated cave dwellings known as yaodong, widespread throughout northern China would have been uninhabitable without the kang. The kang was also an important feature of traditional dwellings in often-frigid Manchuria, where it was known as nahan in Manchu. It plays an important role in Manchurian mourning customs. The deceased is placed beside the kang instead of in the central hall, as is Han Chinese practice. The height of the board on which the body is placed indicates the family status or age of the deceased. See also Masonry heater Ondol - similar system in Korea Kotatsu Russian stove Hypocaust Underfloor heating Notes References Proceedings of the 9th International Conference on the History of Science in East Asia, held August 23–27, 1999 in Singapore. External links Mud bed influences Chinese ancient culture Architecture in China Chinese inventions Fireplaces Traditional Chinese architecture