The inscription, known as Ma nhai ky cong Thanh Nam, dates back to 1335 during the reign of Emperor Tran Minh Tong and is carved directly onto a cliff in Con Cuong Commune.
Nghe An authorities held a ceremony on May 22 to announce the recognition and present the National Treasure certificate.
According to historical records, the inscription commemorates a military campaign led by retired Emperor Tran Minh Tong against Ai Lao forces in the region corresponding to present-day western Nghe An.
Following the victory, the emperor ordered official Nguyen Trung Ngan to compose the text to affirm national authority and record the military achievement.
The inscription consists of 14 lines and 155 Chinese characters carved into a rock surface measuring about 1.55 metres wide and 2.13 metres high.
Despite nearly seven centuries of exposure to the natural environment, the engraved characters remain largely intact.
Researchers consider it one of the oldest cliff inscriptions in central Vietnam and the second-oldest surviving ma nhai inscription nationwide.
Officials said the recognition highlighted the site’s exceptional historical, artistic and scholarly value, while also reinforcing efforts to preserve and promote Vietnam’s cultural heritage.