Because the yang in the title is different from the sheep in the zodiac.
Yang surname source: from Ji surname. Giving surnames: Giving surnames for meritorious service, and being named as the most popular surname by the rulers for meritorious service, so as to make their families shine and honor their ancestors, is the most basic type of giving surnames. Take care of your master. Change your surname. Return to the old surname. Yang surname of ethnic minorities: Yang Miao and Yang Zaicheng, Miao educators in Yuan Dynasty, from Chengbu, Hunan. Yang, Yang Yingkui, Hui nationality, was a poet, calligrapher and scholar of the Ming Dynasty. Manchu yang, Manchu yang's ancestors are mostly Han Chinese.