In 221 B.C. Qin Shih Huang-di, or the First Emperor of Qin, terminated the long-standing wars among the dukes and princes, united China, and established the Qin Dynasty, the first centralized, unified and multi-national country in the history of China. 

    The centralized, feudalistic, despotic system, introduced and perfected during the Qin Han period, and other measures contributory to unification, such as the prefecture and county system, etc., introduced during the same period, have been modeled upon by all the later monarchs. Thanks to the great progress of the society and economy, the reigns of Emperor Wen and Emperor Jing of the Han Dynasty were distinguished by great order and prosperity, when liberal arts and natural sciences both advanced vigorously.��
    The ��Records of Historian�� written by Sima Qian , the Eight-Dragon Seismograph made by Zhang Heng , the ��Nine-Chapter Book of Arithmetic�� and the ��Yellow Emperor��s Book for Physicians�� , etc., in this period all bore great influences on the coming ages . Cai Lun updated the method of paper making, which was known as one of the Four Great Inventions