How did the poetry of the Southern Song Dynasty develop?

In the late Southern Song Dynasty, with the depression of patriotic will, poetry creation entered a period of decline, and a group of "Jianghu poets" and their works became famous in the poetry world. Among them, except for Liu Kezhuang, Liu Chenweng and Dai Fugu, most of them are not well-known, with a small number of works and limited weather. Writers like the "Four Spirits" re-established the banner of the late Tang Dynasty, taking Jia Dao and Yao He as their ancestors, with low methods and even lower achievements. Fortunately, "the country is unfortunate, but the poet is lucky". The change of national subjugation in the Southern Song Dynasty has created a number of patriotic poets such as Wen Tianxiang and Wang Yuanliang. Their works are both lyrical and highly documentary. They made indelible contributions to the inheritance of Du Fu's "poetic history" tradition and patriotic tradition in the middle and late Southern Song Dynasty, and made a brilliant summary for the Song Dynasty. For example, Wen Tianxiang's famous sentence "Song of Benevolence and Righteousness" and the famous sentence "Who has never died since ancient times, keep the heart of a child and shine on history" ("Crossing the Ocean") have already turned into the soul of the nation and become the precious spiritual wealth of the whole Chinese nation.