Liu Gongquan (778 -865), whose real name is Cheng Xuan, was born in Jingzhao, Tang Dynasty. He was a prince, who was called "Liu" in the world. Because he was also named Duke of Hedong by the emperor, later generations also called him "Liu Hedong". He is a descendant of Yan Zhenqing, and later called them "Yan Liu", which became a model of calligraphy in past dynasties. Together with Zhao Mengfu, Yan Zhenqing and Ou Yangxun, they are also called "Four Great Calligraphers". Yan Ti was a calligrapher of Zhenqing (709 ~ 785) in Tang Dynasty. Chen Qing, a native of Jingzhao Wannian (now Xi, Shaanxi), was originally from Linyi (now Linyi, Shandong). The History of Books is also called Yan. Be upright, be upright. The innovator of calligraphy in the Tang Dynasty set up a banner for calligraphy in the prosperous Tang Dynasty. Yan Zhenqing studied books since childhood and was taught by Zhang Xu. He also studied and developed Cai Yong, Wang Xizhi, Wang Xianzhi and Chu Suiliang, and formed his own unique style. Its regular script is square and dense, the strokes are light and heavy, the brushwork is vigorous and round, and the momentum is solemn and vigorous, so it is called "Yan Ti". His cursive script is ups and downs, concise and vigorous, and is called "Yan Liu" with Liu Gongquan.
Yan Zhenqing has opened up a brand-new realm of calligraphy: in terms of characteristics, Yan has a brand-new figure, strict statutes and great momentum. From the aesthetic point of view, beauty of face and beauty of body are dignified, masculine and artificial, and beauty of number is simultaneous, which sets a rule for later generations. From the perspective of the times, the early Tang dynasty inherited the rest of the Jin and Song dynasties, but failed to stand on its own feet. As soon as Yan style appeared, the new style of Tang Doutan casting became one of the distinctive features of the prosperous Tang Dynasty.