Researchers in Nanjing reveal further evidence of its rich and colorful past.

A city's name can often indicate its status in a nation's history.

Nanjing means "southern capital city" in Chinese. Only Beijing, meaning "northern capital city" can claim such a descriptive identity.

The city, now capital of East China's Jiangsu province, was once widely considered to have an urban history of 2,500 years, but new archaeological research rewrites that. This has found that it was founded more than 3,100 years ago when an ancient city, named "Changgan", was recently excavated.

Dating to the Shang and Zhou dynasties (c.16th century-256 BC), archaeologists found that the "city's walls were flanked by trenches", which is an important indicator of a fortification system used by ancient cities, says Chen Dahai, head of the archaeological excavation team, and an associate professor at the Nanjing Archaeological Research Institute.

Chen made the comments during a seminar last week discussing the latest findings in Nanjing.

In the history of the ancient fortification system, trenches emerged before walls. They surrounded the living area to prevent floods and deter enemies, according to Chen. He says at least four encompassing trenches built in different periods during the Shang and Zhou dynasties were detected.

Aside from portions of the city's walls and trenches, archaeologists discovered a fascinating history of a city with water wells built in the late Shang Dynasty, kilns for brick firing and a pit for pig sacrifices. Covering about 12,000 square meters, the area of Xijie, or west street, has seen more than 500 heritage sites unearthed and more than 10,000 cultural relics, such as pottery vessels, jade discs, ceramics and copper tools.