A period of development of distinctive regional cultures in the central Andes of South America, c 1-600 AD (also said to be c 300-600 AD). The period was characterized by nationalism, full population, first large-scale irrigation works in coastal valleys, interregional warfare, construction of forts, craft specialization, social class distinctions, rise of first great Peruvian cities. Two of the better-known cultures are the Moche and Nasca civilizations. The Middle Horizon emerged from these expansions.