Ancient Society is an 1877 book by the American anthropologist Lewis H. Morgan. Building on the data about kinship and social organization presented in his 1871 Systems of Consanguinity and Affinity of the Human Family, Morgan develops his theory of the three stages of human progress, i.e., from Savagery through Barbarism to Civilization. Contemporary European social theorists such as Karl Marx and Friedrich Engels were influenced by Morgan's work on social structure and material culture, as shown by Engels' The Origin of the Family, Private Property, and the State (1884).