The surname Yang is one for posterity of the Yellow Emperor and the sixth most common family name of the Chinese people. The surname Yang has two main origins, one from the name of a state and the other from the name of a fief. Both originate from the surname Ji, the one used by the direct descendents of the Yellow Emperor - the earliest ancestor of the Chinese people.
Historical records of the surname Yang taking name from a state can be found in writings of Zheng Qiao in the Southern Song Dynasty. The records say the youngest son of King Xuan of the Zhou Dynasty was conferred the title of Marquis Yang. The state Yang was later eliminated by state Jin. Extirpates from state Yang then assumed the name of their state as their surname.
Another origin of the surname Yang is from the name of a fief. Shu Yu, the third son of King Wu of the Zhou Dynasty, was conferred in Jin. When Duke Wu of state Jin succeeded the throne, King Li of the Zhou Dynasty conferred the right of taxation of land Yang (now in southeast of Hongdong of Shanxi province) to him. Duke Wu��s son Bo Qiao was conferred the title Marquis Yang. So began the history of the surname Yang, which took the name of a fief.
After the Northern Wei Dynasty many ethnic minorities changed their surnames to Yang and the surname Yang became a large surname for multiple nationalities.
By People's Daily Online