What is the historical background of the poem "Shan He Ren"

1, although the mountains and rivers are broken, the mountains and rivers last forever, which was written in the second year of Su Zong (757) in March to Germany.

2. In June of the first year, the Anshi Rebellion invaded Chang 'an. "In three days, private wealth was plundered," and the city was set on fire, and the prosperous and magnificent Kyoto was in ruins. In August of the first year, Du Fu placed his wife in Qiang Village _ Zhou, was captured on the way to Lingwu in the north, and was taken to Chang 'an after the fall. It's been over half a year. It was late spring, touching the scene and breaking my heart. I created the five laws that have been passed down for generations.