Since the Song dynasty , critics have called Du Fu the " poet historian " ( 詩史 shī shǐ ) . The most directly historical of his poems are those commenting on military tactics or the successes and failures of the government , or the poems of advice which he wrote to the emperor . Indirectly , he wrote about the effect of the times in which he lived on himself , and on the ordinary people of China . As Watson notes , this is information " of a kind seldom found in the officially compiled histories of the era " .