Communities occupying the central Andean highlands of Peru in the period ad 750 to ad 1000 that were bound together by extensive networks of political and economic control. At the centre of the system was the site of Wari itself in the Ayacucho Valley, which was an urban centre that started as the capital of its region and rose to control surrounding areas. Provincial centres are known at Pikillaqta, Jincamocco, Cajamarca, and the unfinished site of Viracochapampa. Archaeologically, the most distinctive features of the Wari are its architecture and urban planning: great rectangular structures set out on a rigid grid plan that was subdivided into square or rectangular plots called ‘patio groups’. Each patio comprised an open central area edged by long narrow rooms, sometimes two or three deep and up to three storeys high. Few doors allow access between patio groups, and it has been suggested that the intention of Wari architecture is in part to restrict movements within each enclosure. The Wari Empire emerged during the early Intermediate Period as Huarpa cultures interacted with the nearby Nasca Culture at a time of intense interregional exchanges and widespread disruption to existing cultural traditions.