Cardboard was invented in China, about three or four thousand years ago. During the first and second century B.C., the people of the Han Dynasty would use sheets of treated Mulberry tree bark to wrap and preserve foods. Today, cardboard is used for about 80% of product packaging because it is flexible, light weight yet durable and it keeps moisture away from the goods packaged inside.

https://gizmodo.com/how-the-cardboard-box-was-invented-1684626050