"Jiugongge" is a boundary in the history of calligraphy in China, also known as "Jiugongge", that is, draw several large squares on paper, then divide nine small squares in each square, and practice calligraphy against the strokes of the model characters in the calligraphy book.
Nine palace map in the Confucian classic "Book of Changes" also originated from this, so it is called "Luo Shu Nine palace map". The name of "Nine Palaces" has been preserved because of the important position of the Book of Changes in the history of China's cultural development, and it is still in use today.