Calligraphy has gradually become an art in China. Which dynasty?

It should be from the Jin Dynasty. The appearance of Wang Xizhi, a great calligrapher in Jin Dynasty, made the calligraphy art shine brilliantly. His artistic achievements spread to the Tang Dynasty, and calligraphy entered a new realm. Therefore, a number of calligraphers appeared in the Tang Dynasty, such as Ou Yangxun, Yan Zhenqing, Liu Gongquan and other famous calligraphers. They have their own merits and styles in calligraphy attainments. Calligraphy theory in the Tang Dynasty was more rigorous and perfect on the basis of the Three Kingdoms, the Jin Dynasty and the Southern and Northern Dynasties. For example, Sun's Shu Pu, His Shu Duan, and Zhang Yanyuan's Fa Lu were all regarded as the standard by later generations, which had a far-reaching influence on calligraphy theory's creation in later generations.