Si Shao Kang was the king of the Xia Dynasty when he enfeoffed (to give one of his sons freehold property or land in exchange for his pledged service) Zeng Qu Lie, to rule the State of Zeng (Chinese: 鄫, 繒; pinyin: Zēng; Wade–Giles: Tseng, Ts'eng).
The Si's were the descendants of the King Yu the Great of Xia (Si was the surname of the royal house of the Xia Dynasty).
However in 567 BC, the State of Zeng was conquered by the State of Ju. Some of the royal members with the surname Si including the prince of Zeng fled to the State of Lu.
The Prince of Zeng, Zeng Wu, gave his descendants the simplified surname Zeng (曾) in remembrance of the State of Zeng (鄫國).