China is the first country in the world to raise silkworms and weave silk. In ancient China, the working people spun silk from superior cocoons, and the remaining evil cocoons and diseased cocoons were made into silk floss by bleaching. After floating, some residual flocs will be left on the mat.
When the flossing frequency is high, the residual flossing on the pad will accumulate into fiber sheets, which can be peeled off after drying and can be used for writing. This kind of floc is called "He Qi" or "square floc" in ancient books because of its small number of by-products.
The spread of papermaking
Papermaking first spread to Korea and Viet Nam, which are adjacent to China, and then to Japan. Soon after Cai Lun improved papermaking, North Korea and Viet Nam had paper. All countries on the Korean peninsula have learned papermaking. Pulp is mainly extracted from hemp, rattan, bamboo and straw. At the end of the 4th century, Baekje learned to make paper with the help of China people, and soon North Korea and Silla also mastered the paper-making technology. Since then, South Korea's papermaking technology has been continuously improved. During the Tang and Song Dynasties, Korean leather paper was exported to China.
Baidu Encyclopedia-Papermaking (One of four great inventions of ancient china)