This poem, from Du Fu's Car Shop, is a political satire against Tang Xuanzong's belligerence, which may have been written in Tianbao Ten Years (75 1).
After Tianbao, wars between Tang Wang and Tang Dynasty and ethnic minorities in the border areas of China became more and more frequent, and the nature of wars changed from preventing intrusion and stabilizing the border areas before Tianbao to cruel conquest.
Years of campaigns have brought profound disasters to the frontier nationalities and the people of the Central Plains.
This poem is probably written for this purpose.
Tens of thousands of people died in the battle of Shibaocheng. The army was defeated and 60,000 people died. In order to supplement the troops, Yang Pai suggested separating people and sending flail to the military office, and the visitors were shaking with tears. The picture above is a description of this.