The Great Wall of China was completed about 500 years ago, and it still continues to hold surprises. Recently, researchers discovered more than 130 secret doors in it.

According to Xinhua news agency, all the doors were designed to blend in well with the local landscape and be as invisible as possible. They were discovered by the research team of the Great Wall defence system through continuous filming of the unique architectural object with almost a centimetre resolution.

These doors were used to allow reconnaissance teams to pass through. Some were also built as communication channels between the inside and outside of the Great Wall. In addition, they were used for trade in ancient times.

According to some documents from the Ming Dynasty (1368-1644), the doors were allowed to be used by nomadic tribes to graze cattle between Qinghai in northwestern China and the Hetao area, where there was plenty of grass and water. This is evidenced in particular by the fact that some doors are so large that two horses can pass through them in both directions.

Although the existence of passageways in the Great Wall was known before, they have been studied very little. In particular, scholars of the Tang, Song, Ming, and Qing dynasties mentioned the doors. However, there was no material evidence of the existence of such objects before. The new discovery may provide additional information about the mechanism of use of the structure.

The passageways are arranged in such a way that the side facing the potential enemy remains disguised with bricks. And vice versa, the side where the defenders are supposed to be has a cavity. It is almost impossible for the enemy to distinguish between the exit and the exit, but the Chinese army can easily break the protective barrier and launch a surprise attack. Scholars have called this a remarkable demonstration of the military wisdom of ancient China.

Earlier OBOZREVATEL told about a startling discovery that proved the Mayan calendar is more ancient by several centuries than previously thought.

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