Han Dynasty is one of the most important dynasties in the history of China, during which period there were many remarkable achievements. It opened to other cultures for the first time, and had a prosperous foreign trade. The Silk Road exploited in Han Dynasty leaded to West Central Asia. Various arts boomed and many great works of literature, history and philosophy sprung up in this period. The first Chinese dictionary was compiled in 100 AD, with 9000 words providing meanings and listing different writing methods. At the same time, science and technology also made great progress, paper, sundials and the machine for measuring earthquake all invented in this Dynasty. Han Dynasty lasted for 400 years, but the corruption of the ruler resulted in its extinction.