In terms of historiography, the expeditions of the second campaign are significant for providing detailed information on the various peoples of the Korean Peninsula and Manchuria, such as Goguryeo, Buyeo, Okjeo, Ye, and Yilou. The expedition, unprecedented in scale in those regions, brought first-hand knowledge about the topography, climate, population, language, manners, and customs of these areas to Chinese cognizance, and was duly recorded into the "Weilüe" by the contemporary historian Yu Huan. Though the original "Weilüe" is now lost, its contents were preserved in the "Records of Three Kingdoms", where the reports from the Goguryeo expedition are included in the "Chapter on Eastern Barbarians" (東夷傳, "Dongyi Zhuan") — considered the most important single source of information for the culture and society of early Korean states and peoples.