What is the time classification of ancient poetry?

Ancient poetry is the general name of China's ancient poetry, which refers to 1840 China's poems before the Opium War. From the perspective of meter, ancient poetry can be divided into ancient poetry and modern poetry. Taking the Tang Dynasty as the boundary, the previous poems were all ancient poems, and later, the ancient poems gradually declined and died out. Ancient poetry is also called ancient poetry or ancient style; Modern poetry is also called modern poetry. From the Book of Songs to Yu Xin in the Southern and Northern Dynasties, they are all ancient poems, but the poems after the Tang Dynasty are not necessarily modern poems, specifically in the distinction between rhyme and meter.