"Yes," Si Fuqing looked at him and spoke slowly, "These years have been fraught with wars, and even a small fire could lead to serious consequences. If these blueprints are lost, it would be a great loss to both the Mo family and the Great Xia Dynasty."
Mo Yanwen had mentioned that about three hundred years ago, a massive fire burned the Mo family's hidden weapons pavilion to the ground, destroying ninety percent of the blueprints.
Because some of the Mo family's secret hidden weapons were never shared outside the family, there were no copies for some blueprints.
Some blueprints were salvaged and redrawn, but hidden weapons rely on precision and interlocking parts. If one component is misaligned, the entire assembly fails.
The fire came mysteriously, causing significant damage to the Mo family, and the cause was never discovered.