A 4,000-kilometer-long "Second Great Wall of China" has been discovered.

(Dan Tri Newspaper) - While China's Great Wall has long been considered a unique defensive structure, another ancient wall system has unexpectedly been discovered.

Location of an important architectural structure and a trench running along the terrain in Mongolia (Photo: Scitech Daily).

A recent archaeological excavation in Mongolia has revealed surprising findings about a massive ancient wall system, challenging long-held notions about the purpose of border defense structures.

Scientists from Hebrew University (Jerusalem) and Mongolian National University have just published the results of excavating a part of the Medieval Wall System (MWS) – a vast network stretching up to 4,000 km, spanning the territories of present-day China, Mongolia, and Russia.

The research focuses on the approximately 405-kilometer-long "Mongolian Arc," constructed between the 9th and 12th centuries, during the Jin Dynasty.

Although it cannot compare to the legendary Great Wall of China with its total length of 21,196 km, this system still attracts special attention from international archaeologists because of the mysteries surrounding its true function.

The unexpected function of the ancient city walls.

Contrary to the popular belief that ancient city walls were built to prevent invasions, findings from the research team suggest that the MWS system was not a traditional military defense system.

According to Professor Gideon Shelach-Lavi, head of the archaeological team, most of the structures in Mongolia were merely shallow ditches and trenches, insufficient to deter enemy troops. This led to a compelling new hypothesis: the wall may have been built to demarcate territory and control movement in the border region.

The presence of regularly spaced fortifications along the wall further strengthens this hypothesis, suggesting it served as checkpoints to monitor people, livestock, and goods, rather than as a large-scale defensive line against invasion.

The project is "soft" but has received significant investment.

The map shows the location of the wall system that stretched across East Asia (Image: Scitech Daily).

Although not built for direct combat, the MWS system still received significant investment. Archaeologists have found Song Dynasty coins, iron artifacts, and traces of military barracks, indicating that soldiers and officials were permanently stationed there to monitor the area year-round.

However, this system ultimately failed to sustain the Jin dynasty. In the 13th century, the empire collapsed at the hands of the Mongols, and with it, the aforementioned wall system gradually fell into oblivion.

These groundbreaking discoveries are contributing to a change in traditional understanding of ancient border structures in the Eurasian region.

Accordingly, city walls were not only shields against invaders, but could also be tools for territorial governance, controlling the flow of people, and asserting sovereignty through symbolic structures, rather than being purely military in nature.

Source: https://dantri.com.vn/khoa-hoc/tim-thay-van-ly-truong-thanh-thu-2-dai-4000-km-20250602063922993.htm