Why is Du Mu called by later generations?

The word is beautiful, claiming to be Shaoling Yelao, now a native of Gongyi, Henan. A great realistic poet in Tang Dynasty, as famous as Li Bai, was called "Du Li" by the world. In my early years, I traveled north and south, and made many friends like Li Bai on the way. I went to the capital Chang 'an twice to catch the exam, but I didn't get in. Du Fu had great ambitions all his life, but unfortunately he didn't have a chance to realize them. He once worked as a left gleaner and worked beside the emperor. Before long, he angered the emperor by his rude remarks and was removed from his official position. During the Anshi Rebellion, he was scattered everywhere. Later, with the help of friends, a thatched cottage was built in the western suburbs of Chengdu, Sichuan, and settled down temporarily. At that time, Yan Wu, our commander in chief guarding Bo, saw that Du Fu was very talented, so he was invited to be the Minister of Industry of the Staff School, so later generations also called Du Fu "Du Gongbu". After Yanwu's death, Du Fu lost his dependence on life and began to wander again. At the age of 59, he died on a ship from Changsha to Yueyang. The content of Du Fu's poems is extremely extensive and profound, which comprehensively reflects the process of Tang society from prosperity to decline, and has won the reputation of "epic". His poems are diverse in subject matter, rich in variety, deep and gloomy in style, and intriguing in language, reaching the level of perfection. Du Fu was honored as a "poet saint" by later generations. The author of Du Gongbu's works.