The origins of literature can be traced back to the ancient Greek and Roman narrative arts such as Homer's Iliad and Odessey. These works are considered the origin of literature because they provide the earliest literary works describing ancient wars and political events. In ancient China, the Book of Songs and the Songs of Chu were the earliest works of poetry. They reflected the culture and social style of the Pre-Qin period. During the Middle Ages, the origins of literature shifted to knight literature and epic literature such as League of Legends and World of Warcraft. These works described the adventures of medieval knights and reflected the social and cultural background of the time. The origin of modern literature shifted to novels and plays such as Harry Potter and Water Margins. These works provided the earliest modern literary works describing human life and social contradictions. The origin of literature can be traced back to ancient greece and rome, where the art of narration provided the earliest literary works, reflecting the culture and social style of the medieval period, and then transferred to modern novels and plays, providing the earliest modern literary works.