Do you know which is the earliest ancient poem of China?

The earliest ancient poetry can't be verified, and it is generally considered as The Book of Songs.

The earliest seven-character poem has three versions:

First, it is thought to be the Song of Yan by Cao Pi of the Three Kingdoms (Guo Xiliang and others);

Second, some people think it is Zhang Heng's Four Sorrow Poems in the Eastern Han Dynasty (represented by the History of China Literature compiled by the Institute of Literature of China Academy of Social Sciences);

Third, The Fair is the earliest and most complete seven-character poem in existence (Songhui Zhang)