The Duke of Zhou established Luoyi, which was called the Eastern Capital. Later, King You lost the Western Zhou Dynasty, and his son moved eastward to Luoyi, which became the Eastern Zhou Dynasty. The Eastern Zhou Dynasty was already similar to the princes. Therefore, the poems that moved to the royal city of Luoyi were called Wang Feng, that is, the poems of the kingdom, which are the same as the poems of the vassal states.
See Zhou Zhenfu's "Translation and Annotation of the Book of Songs"