Was Sima Yan a calligrapher in the Three Kingdoms period?

Not a calligrapher.

Emperor Wu of Jin Dynasty (16,236-290) was born in Kawachinofumi (now Wenxian County, Jiaozuo City, Henan Province). He was the founding monarch of the Jin Dynasty and reigned from 265 to 290. Sima Yan is the grandson of Sima Yi, the eldest son of Si Mazhao, and the grandfather of Si Marui, Emperor Wu of Jin Dynasty. In 265, he attacked his father, Duke Xiang of Jin, and a few months later forced Cao Huan, Emperor of Wei Yuan, to cede his title to himself and make Luoyang his capital. In 279, Du Yu and others were ordered to divide their forces and attack the State of Wu. The next year, Wu was destroyed and the whole country was unified. After the founding of People's Republic of China (PRC), a series of economic measures were taken to develop production. The household system was promulgated in the first year of Taikang, including the system of occupying land, household modulation, and the system of accumulating officials to occupy land and shady customers. During the reign of Taikang, there was a scene of prosperity, which was called "the rule of Taikang" in history. However, after Wu's demise, he gradually became lazy and extravagant. In 290, Emperor Wu of posthumous title died in a temple. Sai-jo was buried in Junyang Mausoleum.