The Tang Dynasty ruled China from 618-907 CE. It was a period of expansion and cultural flourishing similar to the Han Dynasty. Confucianism was dominant in government and civil service exams were used to select administrators. The Tang extended Chinese influence into Korea, Japan, and along the Silk Road through Central Asia. However, the empire grew weak due to conflicts like the An Lushan Rebellion sparked by the emperor's obsession with a concubine, Yang Guifei. This led to political and economic decline until the Song Dynasty reunified China.