Answer
Sima Yan was the founding emperor of the Jin dynasty, which ruled from 265 to 420. He was a descendant of Sima Qian, a famous historian of the Han dynasty. Sima Yan came to power after overthrowing the Wei dynasty in 265. He was a strong and capable ruler, and under his leadership, the Jin dynasty prospered. However, the dynasty eventually collapsed due to internal conflicts and external threats.