Archaeologists have discovered a series of secret tunnels and corridors beneath the stone city of Houchengzui with six main passageways, acting as a traffic network.
Tunnel under Houchengzui city. Photo: CASS
The recently discovered tunnels in Houchengzui range in depth from 1.52 m to 6.06 m below ground level. The tunnels are between 0.91 m and 1.82 m high and 1.21 m wide. Some tunnels even extend beneath the city walls, providing access to the outside, according to a statement from the Inner Mongolia Institute of Archaeology and Cultural Relics under the Chinese Academy of Social Sciences (CASS), Ancient Origins reported on January 2.
The secret tunnels beneath Houchengzui provided an additional layer of protection to complement the city’s existing defenses. The Neolithic city featured a complex defense system that included three layers of walls, supporting structures along the walls, several guard gates, and strategically located ditches. Archaeologists hypothesize that Houchengzui’s design was motivated by its importance for military defense and its pivotal position on the periphery of the ancient confederacy.
According to Chen Xingcan, director of the Institute of Archaeology, the Houchengzui, Bicun, and Shimao sites form a cultural system that plays an essential role in the study of the formation of complex early societies. The three stone cities in the area provide insights into the civilization along the Hun River.
Houchengzui Stone City is an archaeological site located on the north bank of the Hun River in Qingshuihe County, Inner Mongolia Autonomous Region. Based on previous excavations, the city was founded 4,300 – 4,500 years ago, during the Longshan period. Archaeologists first discovered the city in 2005 and began systematic excavations in 2019. Covering an oval-shaped area of 138 hectares, Houchengzui includes both the inner city and the outer city. The city is fortified by a solid three-layer defense system.
The excavations at Houchengzui revealed three separate city gates. The main gate (CM1) is centrally located on the outskirts of the city and is rectangular in shape, reflecting careful planning and design. The other two gates (CM2 and CM3) add complexity to the city’s entry and exit points. The team also discovered a small cemetery in the southwest of the city, consisting of eight stone tombs in vertical rectangular pits. These tombs are characterized by facing southeast, measuring 175–200 cm long, 40–60 cm wide, and 30–50 cm deep. The tombs have a flat floor and four walls built with hanging ropes.