It's an attempt to enter the 4,000-year-old Houchengzui Stone Ancient City, with its elaborate system of fortifications, cascading defensive walls, and overwhelming armed settlers. But that's not all. Until then, what archaeologists had been unable to discover was a series of secret underground passages and tunnels – a total of 6 tunnels intersecting each other to form a hidden transportation network!
An ancient tunnel network has been unearthed at the Shichengmen Gate in Houchengzui, China. Source: Chinese Academy of Social Sciences/China Archaeological Network
A tunnel running through the entire length of the fortifications
Archaeologists report that recently discovered tunnels vary in depth, ranging from about 5 feet (1.52 meters) to about 20 feet (6.06 meters) below the surface. The interior of these tunnels ranges from 3 feet (0.91 m) to 6 feet (1.82 m) and is about 4 feet (1.21 m) wide.
Entrance to the underpass. (Chinese Academy of Social Sciences/China Archaeological Network)
According to a press release issued by the Institute of Cultural Relics and Archaeology of the Inner Mongolia Autonomous Region through the Institute of Archaeology of the Chinese Academy of Social Sciences and the China Archaeology Network, some of these tunnels even extend under the city walls, providing access to the outside environment.
The TD1 and TD2 tunnels are represented by a blue dotted line on the map. (Chinese Academy of Social Sciences/China Archaeological Network)
The secret tunnels of Houchengzui Stone City meant that an additional layer of security barrier had been added to the existing city defenses. The Neolithic city was already equipped with a complex defensive system, including three concentric walls, supplementary structures along the walls, a limited number, well-defended gates, and strategically located moats.
Archaeologists speculate that the design of Houchengzui Stone City stemmed from the cultural significance of its military defense and its strategic location on the periphery of an ancient city-state alliance.
Panoramic view of Houchengzui Stone City. (Chinese Academy of Social Sciences/China Archaeological Network)
As early as 2022, Chen Xingcan, director of the Institute of Archaeology of the Chinese Academy of Social Sciences, told China Daily: "The Houchengzui, Bicun, and Shimo sites constitute a cultural system, which is crucial for studying how complex societies were formed in the first place." "There is a similar culture with regard to the discovery of two other sites from the same period.
"Many questions remain unanswered. If these sites are military fortifications, who are they defending against?" Chen concluded.
"The work has only just begun, and there is still a long way to go to get more clarity [and] a connection between them."
In conclusion, archaeologists at the time deduced that the study of these three important stone cities in the area would provide a fresher perspective on the civilization along the river.
Houchengzui Stone City: Strategic Urban Planning and Tombs
Houchengzui, also known as Houchengzui Stone Town, is an archaeological site located on the north bank of the Hunhe River in Qingshuihe County, Mongolia Autonomous Region. According to the Antiquities Daily, based on previous excavations, the city's origins can be traced back to the Longshan period, about 4,300 to 4,500 years ago. Archaeologists first discovered Houchengzicheng in 2005 and began systematic excavations in 2019.
This historical period saw the emergence of late Neolithic societies, including the Black Pottery Culture or the Longshan Culture. Covering an area of about 341 acres, Houchengzui is oval in shape and consists of an inner city and an outer city. The city also has a strong triple defense.
Excavations at Houchengzui have revealed three distinct gates: The main city gate (CM1), located in the center of the outer city, is rectangular in shape, suggesting elaborate and well-thought-out urban planning and strategic architectural planning. The Urn City Gate (CM2) and the Outer Urn City Gate (CM3) further add to the complexity of the city entry points.
Close-up view of the main city gate. (Chinese Academy of Social Sciences/China Archaeological Network)
As far as the current discoveries are concerned, no large burials have been found in the Houchengzui archaeological site. However, a small cemetery was found on the southwest side of the city, consisting of eight rectangular pit tombs.
Panorama of tomb excavations. (Chinese Academy of Social Sciences/China Archaeological Network)
The tombs share common features in that they all face southeast, are 175 cm to 200 cm (68.89 in to 78.74 in) long, 40 cm to 60 cm (15.74 in to 23.62 in) wide, and about 30 cm to 50 cm (11.81 in) deep. These tombs are based on flat stone slabs and the four walls are built with slings, forming a unique architectural style of these tomb structures.
Reference: Chinese Academy of Social Sciences/China Archaeological Network