Inside the tomb of the emperor

The opening of the Impregnable Wall. The man on top of the left ladder is Zhao Qichang. [Photo provided to China Daily]

In the late 1980s Yang, together with Yue Nan, a historian, wrote the book Wind and Snow at Dingling (feng xue ding ling), a vivid recount of the entire excavation process.

In the 1950s, when some leading historians and archaeologists in China decided to excavate an imperial tomb from the Ming Dynasty for research, Dingling (1368-1644) was not even near the top of the list, Yang says.

"They initially focused on other tombs, tombs either belonging to a historically more important Ming Emperor or standing the chance of housing crucial information, imperial tomes for example."