Qin Dynasty: 221 BC to 206 BC

Historians often refer to the period from Qin Dynasty to the end of Qing Dynasty as Imperial China. Though the unified reign of the Qin Emperor lasted only 12 years, he managed to subdue great parts of what constitutes the core of the Han Chinese homeland and to unite them under a tightly centralized Legalist government seated at Xianyang (close to modern Xi'an). The doctrine of legalism that guided the Qin emphasized strict adherence to a legal code and the absolute power of the emperor. This philosophy of Legalism, while effective for expanding the empire in a military fashion, proved unworkable for governing it in peace time. The Qin Dynasty is well known for beginning the Great Wall of China, which was later augmented and enhanced during the Ming Dynasty. The other major contributions of the Qin include the concept of a centralized government, the unification of the legal code, written language, measurement, and currency of China.