Book of Documents
There are few references to Hanzhong before the Qin dynasty's unification of China in 221 BC. The "Book of Documents" refers to an area called Liangzhou (), while Sima Qian's book "Records of the Grand Historian" speaks of a "Bao state" (, where the ancient beauty Bao Si came from), both of which are believed to refer to the area now called Hanzhong.