Sui Yangdi
The first Sui emperor, Emperor Wen of Sui established the two tier "zhōu" and "xiàn" territorial administration system, renaming Xingzhou () Zhengzhou in 583 CE and thus establishing the official name of the city that still exists today. After Emperor Yang of Sui improved both the Grand Canal and its Western extension the Tongji Canal () for a time Zhengzhou became an important national hub for both land and water borne commerce. In 618 CE Sui General Yuwen Huaji killed Emperor Yang of Sui marking the end of the Sui Dynasty. Thereafter, Yang Tong seized his opportunity and set himself up as emperor in Luoyang. A year later General Wang Shichong nullified Yang's appointment and reestablished the State of Zheng, the third iteration of the name in Chinese history. In 621, Li Shimin (later Emperor Taizong of Tang ) led three thousand armored horsemen to face Dou Jiande's 100,000 strong army at the Battle of Hulao. Dou lost and Wang Shichong immediately surrendered Luoyang.