Zheng (; Old Chinese: *) was a vassal state in China during the Zhou Dynasty (1046–221 BCE) located in the centre of ancient China in modern-day Henan Province on the North China Plain about east of the royal capital at Luoyang. It was the most powerful of the vassal states at the beginning of the Eastern Zhou (771–701 BCE), and was the first state to clearly establish a code of law in its late period of 543 BCE. Its ruling house had the surname Ji (姬), making them a branch of the Zhou royal house, who were given the rank of Bo (伯), corresponding roughly to a countdom.