The Battle of Red Cliffs was a decisive battle at the end of the Han Dynasty, immediately prior to the period of the Three Kingdoms in China in the northern winter of 208 CE between the allied forces of the southern warlords Liu Bei and Sun Quan, and the numerically superior forces of the northern warlord Cao Cao. Liu Bei and Sun Quan successfully frustrated Cao Cao's effort to conquer the land south of the Yangtze River and reunite the territory of the Eastern Han Dynasty. The allied victory at Red Cliffs ensured the survival of Liu Bei and Sun Quan, gave them control of the Yangtze, and provided a line of defence that was the basis for the later creation of the two southern kingdoms of Shu Han and Eastern Wu. For these reasons, it is considered a decisive battle in Chinese history. Descriptions of the battle differ widely on details; in fact, even the location of battle is still fiercely debated. The most detailed account of the battle comes from the biography of Zhou Yu in the 3rd-century historical text Records of Three Kingdoms. An exaggerated and romanticised account is also a central event in Romance of the Three Kingdoms, one of the Four Great Classical Novels of Chinese literature.