ZHENGZHOU, June 21 (Xinhua) -- Four ancient kiln relics have been unearthed in central China's Henan Province, local archaeologists said Friday.

Although the flue of one kiln had been destroyed, the other three were well preserved.

The four kiln relics, covering about 170 square meters, were found in late May in Weidu District of the city of Xuchang. The space between each kiln relics is about two meters, according to the city's archaeological research institute.

According to the structure and unearthed relics from the ancient kilns, archaeologists said they can date back to the Tang Dynasty (618-907) and the Song Dynasty (960-1279). The kilns were used for making bricks and tiles for building.

Two of the kilns' floor had been renovated with signs of thick sintering surface, showing the kilns had operated for a long time.

The kiln relics provided detailed materials for research on the level of local social productivity in the dynasties of Tang and Song, archaeologists said.