Why is Tang poetry divided into four periods in literature?

Every dynasty has its own literary form, among which in the Tang Dynasty, poetry is the most common literary form, and many poets emerged in the Tang Dynasty, who pushed the development of poetry to a new peak, and poetry became more and more perfect in the process of historical development, which is closely related to the development of the Tang Dynasty. Poetry in the history of literature can be divided into four periods, because these four historical periods all represent the different development stages of Tang poetry, and they are also the process of Tang Dynasty's prosperity and decline.

First, in the early Tang Dynasty, because the art form of poetry just appeared, many aspects were in a preliminary state, and there were many places that needed to be developed and improved, similar to the newly established Tang Dynasty. Moreover, at that time, the Tang Dynasty had just put down the war, and everything was in a state of desolation, which was the same as the development of poetry. Poetry at this time is not so famous, so there are not many poets to create poetry.

Second, in the middle and late Tang Dynasty, poetry had developed very well. Poetry, in terms of meter and rhyme, has been greatly improved compared with the early Tang Dynasty. At this time, the Tang Dynasty was also the most vigorous stage of development. Moreover, because the ideas of the Tang Dynasty were relatively open and the rulers advocated poetry as a literary form, the number of poems also increased sharply, and the number of poets also increased, which was also a historical development.

Third, in the late Tang Dynasty, due to the complacency of the rulers, the overall strength of the Tang Dynasty was not as good as before, and there were serious disturbances all over the country, and the rulers were also self-sufficient. At that time, the prosperous Chang 'an was also in ruins, and the people were separated and miserable because of the war. At this time, Tang poetry also entered a downhill stage, and most of the poetic styles began to turn to realism. For example, Du Fu's poems are a true portrayal of people's lives at that time.