Ssu-ma Yen began the Chin Dynasty; he ruled from 265-289A.D. As an emperor, he was called Wu Ti. The Chin managed to reunify China when, in 280 A.D., they conquered the Wu Kingdom, thus ending the period of The Three Kingdoms. Despite this success, they were not a stable empire. After defeating the Wu, there was no longer a serious danger of being invaded. Therefore, the emperor declared the armies should be disbanded, and all the arms returned. However, this did not occur in every region. The princes, most of whom had been given their titles due to their relationship to the emperor, declared they needed personal guards. The discharged soldiers belonged mainly to the state and didn't give up their weapons either. Instead, they sold them, mainly to the Hsiung-nu and the Hsien-pi. This was a fatal mistake of the Chin government, as it made them virtually powerless, while all their rivals and enemies gained power.

After the death of Ssu-ma Yen, there was never again a strong leader. The leaders and princes were often assassinated in the struggle for power. During this time, the Chinese people surrounding the capital suffered due to the fighting and began a migration out from the center of the empire to the more peaceful frontier regions.

The Chin were eventually defeated by the Huns, who claimed they were descendents of the Han Dynasty because of the Han princesses given to them in marriage. However, they never succeeded in forming a true dynasty and uniting China. Rather, the disunity continued with the Northern and Southern dynasties. The defeated Chin fled and from 317-420 they ruled as the Eastern Chin in Nanking.