In the early Tang Dynasty, from Li Shimin of Emperor Taizong to Kaiyuan of Emperor Xuanzong of Tang Dynasty, the country was in a stage of great development, with unprecedented prosperity in economy, politics, military affairs, diplomacy and culture. During this period, "Zhenguan rule" and "Kaiyuan Shi Sheng" formed the prosperous weather of the Tang Dynasty that the Chinese nation was proud of. Therefore, China once stood out in the world. The Anshi Rebellion in the later period of Xuanzong in Tang Dynasty made the Tang Dynasty gradually decline. In the middle and late Tang dynasty, the emperor had no real power in economy, politics and military affairs, which led to the formation of the separatist situation in the buffer regions. Finally, all parties broke away from the rule of the Tang Dynasty and became independent regimes. There were 22 emperors in the Tang Dynasty who lived in China for 290 years (during which Wu Zetian changed the Tang Dynasty to sixteen years). Together with the Han Dynasty, it is called one of the two powerful dynasties in the history of China. At its peak, its territory was in the east of Andong Prefecture (now Pyongyang, North Korea), in the west of Anxi Prefecture (now Kuqa, Xinjiang), in the south of Rinan County (now Qinghua, Vietnam) and in the north of Anbei Prefecture (now Harrah and Forest, Mongolia). After the Anshi Rebellion, Hexi and Longyou were trapped in Tubo until Dazhong (847-860) and Xian Tong (860-874). In the early Tang Dynasty, from Li Shimin of Emperor Taizong to Kaiyuan of Emperor Xuanzong of Tang Dynasty, the country was in a stage of great development, with unprecedented prosperity in economy, politics, military affairs, diplomacy and culture. During this period, "Zhenguan rule" and "Kaiyuan Shi Sheng" formed the prosperous weather of the Tang Dynasty that the Chinese nation was proud of. Therefore, China once stood out in the world. The Anshi Rebellion in the later period of Xuanzong in Tang Dynasty made the Tang Dynasty gradually decline. In the middle and late Tang dynasty, the emperor had no real power in economy, politics and military affairs, which led to the formation of the separatist situation in the buffer regions. Finally, all parties broke away from the rule of the Tang Dynasty and became independent regimes.
When the peasant uprising was surging at the end of Sui Dynasty, Li Yuan, who stayed in Taiyuan in Sui Dynasty, took the opportunity to attack Chang 'an. In the first year of Wude (AD 6 18), Li Yuan was proclaimed emperor by the Zen ancestor Sui, and the Tang Dynasty was established, with Tang Gaozu as its capital. Li Yuan and his son Li Shimin wiped out separatist forces in various places, suppressed peasant rebels and unified the whole country.