Archaeologists excavating at Houchengzui in Inner Mongolia Autonomous Region have uncovered a network of ancient tunnels.
Houchengzui, also known as Stone City, is an archaeological site located on the north bank of the Hun River in Qingshuihe County in the Inner Mongolia Autonomous Region. Previous excavations have dated the city to around 4,300 to 4,500 years ago, the period when late Neolithic societies such as the Black Pottery or Longshan culture emerged.
Covering an area of about 341 acres in an oval layout, Houchengzui consists of both an inner and outer city reinforced by a triple defense system of ditches and walls.
According to an announcement by the Institute of Archaeology of the Chinese Academy of Social Sciences (CASS); Excavations revealed an ancient transportation network as well as an underground network of tunnels used for defense and attack.
A total of 6 underground tunnel passages, between 1.5 and 6 meters deep, radially radiating from the city center were discovered. The tunnels have an arched ceiling, similar to the cave dwellings of the Longshan culture, and are about 1 to 2 meters high and 1.5 meters wide.
According to Sun Jinsong, director of the Cultural Relics and Archaeology Academy of Inner Mongolia, the outer defensive walls (known as barbicanes) as well as the surrounding moats were the focus of recent research.
The excavations also uncovered three city gates: the main city gate (CM1), the cube city gate (CM2) and the outer cube city gate (CM3). The main city gate is located in the center of the outer city wall, is rectangular in plan and has a gate entrance flanked by earthen platforms on both sides.
Archaeologists also found other defensive structures, including city walls and bastions. It is clear that the city of Houchengzui attached great importance to military defense. Excavations at the site are still ongoing.