"Making porcelain using a Tongguan kiln requires at least six kinds of raw materials such as clay, sand and subsoil," Liu says.

"It takes at least 10 days, and more than 10 meticulous and laborious procedures, including clay concoction, molding, pinching, painting and glazing, before a piece can be fired at a maximum temperature of 1,280 C," Liu adds.

At a recent archaeological exhibition that showcased achievements of the past 70 years, a celadon-glazed porcelain bowl from Tongguan stood out among other ancient relics with its inscriptions of an ancient lotus-picking poem.

The bowl dates back to the Tang Dynasty (618-907) and was displayed at the Changsha Museum. The poem on it is not included in the Complete Tang Poems, a massive collection of Tang poetry, just as many of its counterparts were found to be inscribed with lesser-known poems of that era.

The poems faithfully record what life was like in Changsha during the Tang Dynasty, and most of them were authored by kiln workers and other common people, says Zhang Haijun, deputy curator of the museum.