The characters carved on the stone tablet are Chinese characters. As the range of influence of the ancient Chinese civilization circle, it is not surprising for Leonard Ethan to see Chinese characters here.
After all, during the age when this secret chamber was built, which was during the Tang Dynasty era, this place had a close connection with China. Naturally, the Chinese people left a large number of historical relics here.
To give a simple example, Suizheng City, the birthplace of Li Bai, the great poet of the Tang Dynasty in China, is only a few hundred kilometers east of Leonard Ethan's current location, near Tokamak.
Although this place was not part of the ancient Chinese territory, it belonged to one of China's vassal states at that time. More importantly, the historically important Silk Road passed through here, so the appearance of Chinese characters is quite reasonable.