BEIJING - The Chinese capital's future administrative hub was already bustling 2,000 years ago.

Government agencies excavating a site in the far southeastern Beijing suburbs say they have found ancient city walls and more than 1,000 tombs, most of which are dated to the eastern Han Dynasty (25-220 AD) and some even earlier.

The excavations, made this year ahead of development of a new administrative district for Beijing, shed light on life in a county-level city that was alive with activity several hundred years earlier than experts previously thought. Archaeological teams this year found ceramic and porcelain urns, earthen sculptures of animals, copper tools and mirrors - some of which are believed to be made by the Yan, a northern kingdom that stood for centuries before falling to the conqueror who unified China and became its first emperor in 221 B.C.

The excavators also found ruins of a square-shaped city with walls 600 metres on each side from the Han Dynasty.

Modern Beijing suffers from traffic gridlock and overcrowding with 22 million residents, prompting officials to relocate many government agencies from the city centre to a newly developed site in the suburb of Tongzhou, about 24 kilometres away. Under President Xi Jinping's calls for China to show greater "cultural self-confidence," local-level governments have been touting their respective historical relics and archaeological finds.

Beijing officials said this week they would assess the archaeological value of some of the artifacts. High-value ruins at the site could prompt changes to development plans for the administrative zone.

Tongzhou is mostly known today as a bedroom community with soaring apartment blocks housing workers who commute to jobs in central Beijing. The area was previously believed to have been developed in the Sui and Tang Dynasties (581-907 AD), when it became a trading hub on the Grand Canal leading to southern China.

"Our assessment is now that this area was actually quite developed and prosperous earlier than we thought," said Yu Ping, spokeswoman for the Beijing Municipal Bureau of Cultural Heritage