In 265, as a chancellor of the Kingdom of Wei, Sima Yan forced the last emperor of Wei, Cao Huan, to turn over his throne. Soon after Sima Yan acceded to the throne, proclaimed himself Emperor Wu in Luoyang and established the Jin Dynasty. In 280, Sima Yan sent his troops to attack the Kingdom of Wu and eventually defeated the last kingdom of the Three Kingdoms Period (220 - 280). The Jin Dynasty had unified the whole nation.

However, the state of unification did not last long. With the increase of the military strength, some nomadic ethnic groups on the frontier began to wage war to contest the central plains with the Jin Court. After a period of fighting, these groups set up a series of regimes in northern areas, called 'sixteen kingdoms'.

On the positive side, the process of Han-Chinese assimilation with other minority groups was greatly progressed. Meanwhile, the propagation of Buddhism in southern and northern areas became more and more popular. In addition, technological progress in medicine, astronomy and drafting technique was also notable during that time.