Yan Zhenqing, born in 709 BC, was a statesman and calligrapher in the Tang Dynasty. The four emperors he experienced, namely, Emperor Xuanzong of Tang Dynasty, Tang Suzong, Tang Daizong and Tang Dezong, had a rough life. His Yan Kai calligraphy method, excellent economy, laid a solid foundation for later calligraphy learning and creation, which can be described as a generation of saints Yan Zhenqing.
The spread of Yan Zhenqing's calligraphy was preserved by seal cutting, so how did Yan Zhenqing's original works before that survive? In fact, graphite is an inert substance, which is difficult to react with other things, so some original works have been preserved because of the materials used in ancient Chinese characters. But even though graphite is inert and written on paper, it is very fragile and difficult to preserve. So later, someone tried to copy ancient poems and preserved many ancient poems and paintings. There is also a saying that poetry seal cutting has been circulated on stone tablets so far, but in fact, ancient poetry has been known by people now.