Defensive system

Jin Dynasty Emperor Wanyan Liang, who decided to relocate the capital, set up a complete defensive system around Zhongdu to prevent potential attacks from northern Mongolian tribes. The Jin Dynasty was one of the few established by an ethnic minority.

Ding, from the Beijing Archaeological Research Institute, said that before the Tang Dynasty, emphasis on the defensive capabilities of the capital was placed on high walls and deep moats. However, over time, as more artillery was used in military battles, the city wall needed to be improved.

"The city wall was about 16 to 18 meters high and the moat was 66 meters wide. The wall, the moat and other facilities such as a fortified tower shaped like a horse's head constituted the defensive works of Zhongdu," she said.

At the start of the Jurchen regime, the rulers faced resistance and suppression from the nomadic Khitan people. Without sturdy city walls, the Jurchen population could have been wiped out by this strong northern tribe.

Later, the Jurchen people faced threats from the Mongols.

"Outer defense is of paramount importance to an ancient city. Once the outer city walls are breached, defense of the inner city is basically rendered useless," Ding said.

She added that at various periods, all Jin Dynasty rulers introduced policies to encourage farming.

"The emphasis they placed on land and agriculture brought stability, and the Jurchen people, who relied on fishing and hunting for a living, started to settle down, which deepened their dependence on cities," she said.

Although the Zhongdu city gates have not yet been discovered, finding the moat and tower shaped like a horse's head are strong evidence that Zhongdu possessed a complete defensive system as a capital city, Ding said.