as crown prince, crown prince zhuang was often requested by emperor guangwu to render opinions in important matters. in 51, he was involved in making a major correct decision in han's relationship with xiongnu. by that point, xiongnu had a civil war and divided into two—with north xiongnu ruled by chanyu punu (蒲奴) and south xiongnu ruled by chanyu bi (比). han had become allied with south xiongnu, and in response, chanyu punu, also wanting peace with han, requested a "heqin" marriage. prince zhuang suggested that emperor guangwu refuse the proposal, reasoning that north xiongnu had only made the proposal to alienate south xiongnu from han. emperor guangwu agreed.