HANGZHOU, Oct. 17 (Xinhua) -- A well-preserved dragon kiln site dating back to the Eastern Han Dynasty (25-220) has been found in the city of Ningbo, east China's Zhejiang Province. The kiln site can provide crucial evidence for the study of the development history of the Yue kiln, according to the city's cultural heritage research institute.

The Guotang'ao kiln complex site, featuring a 22.5-meter-long dragon kiln, is located in Bazi Village, Cicheng Township of Ningbo. A dragon kiln is a long, sloping chamber having a firebox at one end and a flue at the other.

Named for its dragon-like shape and sloping structure, this kiln features a large firebox about 2.2 meters deep at the front, with a fire door at the base. Remnants of a working platform, post holes and a drainage ditch were also found at the kiln's entrance.

The firing chamber, elevated 1.2 meters above the firebox's rear, ensures proper draft airflow to increase kiln temperature after ignition, said Wang Guangyuan, head of the Guotang'ao kiln site archaeological project.

The kiln bed, with a steep slope of roughly 24 degrees at the front and 28 degrees at the back, along with a fine sand base, best demonstrates the craftsmanship of Eastern Han artisans. This design ensures smooth flame circulation within the kiln, promoting even heating of ceramic wares and enhancing firing efficiency, Wang explained.

At least four layers of repair marks were identified, suggesting prolonged use. Additionally, three semicircular flue pits at the kiln's rear form a complete ventilation system, ensuring consistent airflow and efficient waste gas expulsion.

A large number of daily-use porcelain wares was excavated at the site, mostly with celadon and black glazes and Eastern Han decorative motifs.

The discovery of black-glazed porcelain demonstrates that the Cicheng area of Ningbo had achieved mastery of kiln technology for producing black-glazed wares by the Eastern Han Dynasty, researchers noted. This finding challenges the long-held assumption that such wares were predominantly manufactured in other parts of Zhejiang.

The finding offers new insights into the origins and technological evolution of such porcelain, according to Wang.

The Yue kiln system was one of ancient China's most enduring and influential celadon production systems, spanning the Eastern Han Dynasty to the Southern Song Dynasty (1127-1279).