Papermaking was invented at the end of the Western Han Dynasty. After improvements by Cai Lun in the Eastern Han Dynasty, the papermaking industry developed greatly, and paper began to become a commonly used writing material. The allusion of "Luoyang paper is expensive" can be used as evidence. By the Tang Dynasty, paper had basically replaced other writing materials and occupied a dominant position. The characteristics of paper, such as its ease of rolling, easy portability, and easy drying, have promoted the popularization and development of Chinese calligraphy art.