Wang Mang (45 BC-23 AD) was a great monarch and the founder of a new dynasty. He ruled from AD 8 to AD 23. This new dynasty only existed for fifteen years in the long river of China's 5,000-year history. There is only one emperor. This is the shortest-lived dynasty. (Of course, the dynasty established by Li Zicheng, Zhang and Wu Sangui was even shorter-lived. But these dynasties were only partial, and there was no unification of the new dynasty.