When was Li Deyu born?
Li Deyu
787
Li Deyu was born in 787, during the reign of Emperor Dezong.  His grandfather Li Qiyun (李栖筠) served as the chief imperial censor, and his father Li Jifu would eventually serve as a chancellor during the reign of Emperor Dezong's grandson Emperor Xianzong.  It was said that Li Deyu was ambitious in his youth and was studious, particularly concentrating on the Book of Han and the Zuo Zhuan.  He, however, did not want to submit to imperial examinations.  During Emperor Dezong's Zhenyuan era (785-805), when Li Jifu was in exile, Li Deyu accompanied his father and did not seek an official career.[3]