Is Ji Zi an ancient poem or a modern poem?

Ji Zi is an ancient poem. Guan Ju by Zhou Nanfeng from The Book of Songs. The Book of Songs is a classic of China's ancient poetry, including style, elegance, ode, Nan Zhou, Zhao Nan, national style, Xiaoya, elegance and so on. It is the earliest extant collection of poems in China, written between 1 1 century BC and the 6th century BC. Classical poetry is a form of China's ancient poetry. Compared with modern poetry, it has many differences in rhythm, meter and words.