The State of Cao was a vassal state in China during the Zhou Dynasty (1046–221 BC). The state was founded sometime in the 11th century BC by Caoshu Zhenduo (d. 1053 BC) （曹叔振鐸）, son of King Wen of Zhou and the younger brother of King Wu of Zhou. With its capital at Taoqiu (陶丘), the State of Cao covered roughly the area of modern-day Dingtao County, Shandong Province. It was located on the flat country of the North China Plain about 50 miles east of the point where the current course of the Yellow River changes from east to north-east. To the northwest was Wey, to the northeast Lu and to the southeast Song.