Firstly, the internal reasons for the development of poetry. Everything has its peak. From the pre-Qin Dynasty to the Han, Wei and Six Dynasties, poetry experienced a long history and development process. Those five-character ancient poems, seven-character ancient poems, metrical poems and quatrains all crossed an experimental stage, so poems gradually formed and matured in the Tang Dynasty.
Moreover, at that time, the funds in the Tang Dynasty were very abundant, the people were relatively rich, and the whole country was unified, peaceful and without war. Poets have more time to travel and write poems. This provided a good material environment for poets in Tang Dynasty to create and develop poems.
But I think there is another decisive factor, that is, the kings of the Tang Dynasty liked poetry very much, so they included it in the imperial examination. Therefore, many literati can pass the imperial examination with their own poems and have a bright career through their own poems. Therefore, most of the literati will spend their energy on studying and writing poems, thus creating a large number of poets, thus reaching the peak of poetry in the prosperous Tang Dynasty.
For example, Li Bai, a poet we are familiar with, became a bachelor of Hanlin in the Tang Dynasty through the imperial examination system of selecting scholars by poetry and fu at that time. Dedicated to playing with the king and writing poems.
However, I think that the imperial examination system of selecting scholars by poetry has its drawbacks, because it will make many literati only learn poetry and how to write poetry, and not learn other cultural knowledge, which may make the spiritual world of literati relatively poor but not rich. Maybe I think there may be some literati who write poems day and night in order to learn them, but they didn't become famous in the end and didn't get a good career because of their poems. Finally, many people may study crazily.