The revetment or retaining wall found in Fuzhou was made of wood, according to Chen Pin, a research fellow with the Fujian provincial museum.
"There had been a river and the revetment was used to prevent erosion," state-run news agency Xinhua quoted him as saying. "Such a structure only existed in south China."
They also found the footing of a city wall, which was built during the period of Five Dynasties (907-960).
"By studying the ruins, we learned the techniques these people would have used -- how they built a city," Chen said.
"They dug a trench, filled it with interlaced stone and wood, before compacting it with earth. The discovery verifies descriptions in historical data about the development of Fuzhou city," said Lou Jianlong, head of the cultural relics and archaeological research institute of the Fujian museum.