File photo shows the drainage system excavated in the Pingliangtai Ancient City ruins in Huaiyang, Central China's Henan province. Archaeologists have unearthed a number of pottery drain pipes at a Neolithic site of Longshan Culture dating back more than 4,000 years and believe they form China's earliest and most complete urban drainage system. [Photo/Xinhua]

ZHENGZHOU -- Archaeologists have unearthed a number of pottery drain pipes at a Neolithic site of Longshan Culture dating back more than 4,000 years and believe they form China's earliest and most complete urban drainage system.

The city drainage system was excavated in the Pingliangtai Ancient City ruins in Central China's Henan province. "The pottery pipes were connected with drainage ditches in the city," said Cao Yanpeng, associate research fellow with the Henan Provincial Institute of Cultural Relics and Archaeology.

The development of public facilities and productivity are key indicators to measure the level of civilization in society. The discovery is of considerable significance to the future studies of the ancient city.

Discovered in 1980, the Pingliangtai ruins were once a regional center in the Longshan Culture. A lot of cultural relics, including delicate jade ware and pottery were excavated there, Cao said.

Previously, several wheel ruts dating back at least 4,200 years were also found at the ruins. They are believed to be China's earliest wheel ruts.