Crown Prince Zhuang, as heir apparent to the Chinese imperial throne, is often requested by Emperor Guangwu to render opinions in important matters.

In 51, he had been involved in making a major decision in the Han dynasty's relationship with the Xiongnu.

By that point, Xiongnu had had a civil war and divided into two—with the Northern Xiongnu ruled by Chanyu Punu and South Xiongnu ruled by Chanyu Bi.

Han had become allied with the Southern Xiongnu, and in response, Chanyu Punu, also wanting peace with Han, requested a heqin marriage (literally "peace marriage").

During the Western Han dynasty between 200 and 140 BCE, there had been ten instances of such marriage alliances during between Han “princesses” (one actually was an Imperial princess) and Xiongnu chieftains.

In the closing decade of the second century BCE, Emperor Wu of Ha had arranged the marriage of two Han princesses to kings of Wusun; in 31 BCE, Emperor Yuan of Han had married Wang Zhaojun, a lady of the imperial harem, to Xiongnu chieftain Huhanye.

Prince Zhuang had suggested that Emperor Guangwu refuse the proposal, reasoning that the Northern Xiongnu had only made the proposal to alienate the Southern Xiongnu from Han.

Emperor Guangwu agrees.

At the death of Emperor Guangwu in 57, Crown Prince Zhuang ascends the throne as Emperor Ming.