Ink is one of Four Treasures of the Study. The date of the invention of ink has been lost in history, but from the records of unearthed cultural relics, it can be seen that ink existed at least in the Spring and Autumn Period and the Warring States Period, developed to a certain extent in the Han Dynasty, reached its peak in the Tang Dynasty, and gained national attention. In Song Dynasty, Hu said in Dong Qing Lu: "There were people who painted books with bamboo in ancient times." This is the earliest form of ink. In ancient China, the skill of making ink was very high, and there were famous ink makers. Chao, a famous ink maker in the Southern Tang Dynasty, had superb ink-making skills. The Hui ink he created was appreciated by Li Houzhu, so he was given the title of "national surname" and changed his name to Li Chao. In the Song Dynasty, someone invented tung oil smoke ink. According to He Yuan, a Song Dynasty poet, "Tanzhou specializes in tung oil as ink. The big ones are only a few inches, and the small ones are as big as round money. Every mill can learn from its light. The studio is a point. " This shows that the ink production at that time was to strive for exquisiteness and deliberately pursue the beauty of modeling and ornamentation. According to the historical records of the Song Dynasty, in addition to making tung oil fume and ink, there is also lacquer smoke and ink. During the Yuan and Ming Dynasties, someone wrote a book named Mo Chi for Mo. The book not only records the process and method of ink making, but also records the characters in ancient ink making. A Qing Ren Hu studied all the methods of making ink in history and made many good inks, among which Cang was the most precious as a tribute.