Xi'an (/ˈʃiˈɑːn/, Chinese: 西安), formerly romanized as Sian, is the capital of Shaanxi province, located in the northwest of the People's Republic of China, in the center of the Guanzhong Plain. One of the oldest cities in China, the city was known as Chang'an before the Ming dynasty. Xi'an is one of the Four Great Ancient Capitals of China, having held the position under several of the most important dynasties in Chinese history, including Zhou, Qin, Han, Sui, and Tang.