Archaeologists have uncovered more secrets of the past during a dig in the outer suburbs of Beijing: Ancient city walls and more than 1,000 tombs, dating to the eastern Han Dynasty. And some of the finds may be even older.

Ancient ruins found in Beijing suburb

These ancient treasures were unearthed early this year, ahead of the development of a new administrative district of Beijing. They shed light on life in a county-level city that once was alive with activity -- several hundred years earlier than experts previously thought.

Archaeological teams found ceramic and porcelain urns, earthen sculptures of animals, copper tools and mirrors -- some of which are believed to have been made by the Yan, a northern kingdom that stood for centuries. It fell to the conqueror who unified China and became its first emperor in 221 B.C.

"There are about 10,000 pieces discovered in this cultural exploration of the Beijing suburb. There are a few characteristics with these items. One, they range from a few dynasties in Chinese history and cover a period of about 2000 years. Secondly, there are various categories of items, ranging from pottery to tools used in daily life, like bronze mirrors, currency and so on," said Guo Jingning, deputy director of BJ Municipal Institute of Cultural Relics.

Then, late last month, researchers revealed another discovery. Excavators had found the ruins of a square-shaped city from the Han Dynasty that existed from 25 to 220 AD. The walls run 600 metres on each side. More than 1,000 tombs had been held safely within the earth as the centuries passed by above them.

Before the digging began this year, the area was believed to have been developed in the later Sui and Tang Dynasties, of the years 581 to 907 AD. It was at that time that the area became a trading hub on the Grand Canal leading to southern China.

"Our assessment now is that this area was actually quite developed and prosperous at an earlier time than we had thought," said Yu Ping from BJ Municipal Bureau of Cultural Relics.

Beijing officials said this week they would assess the archaeological value of these newly-found artifacts.

Tongzhou is mostly known today as a bedroom community with soaring apartment blocks, housing workers who commute to central Beijing. Now, it could become famous for the valuable Chinese history it has protected over the ages.