Li Gao
Li Fengji was born in 758, during the reign of Emperor Suzong. His family was part of the Li clan of Longxi — which was descended from Li Gao the founder of the Western Liang state during the Sixteen Kingdoms period, as the Tang Dynasty imperial clan was, but considered distant enough from the imperial lineage that he was not considered part of the imperial clan. After Li Gao, Li Fengji's family traced its ancestry to a line of officials of Jin Dynasty (266–420), Northern Wei, Northern Qi, Sui Dynasty, and Tang, although Li Fengji's grandfather Li Yan (李顏) and father Li Guiqi (李歸期) were both listed without offices.