I know that after unifying china and setting up Qin Dynasty, the Emperor Qin Shi Huang unified the chinese writing characters, weights and measures, currency, size of carriage and moral principles. All these measurements helped him to better rule the people.

thanks for your replay. Any organised, centralized state must be underpinned by a philosopical base that allows the existance and continuance of an effective regime. what was the relation to this in early china, especially Qin and Han dynasty?

Qin Shi Huang burn books and kill confusican scholars, but regarded Legal Phylosophy of Fa School as the philosophical base. In Han Dynasty, it is world-shaking change. Emperor Wu of Han Dynasty ignore all but obly respect confucius and confucian. The high position of Confucian was built up since then.