This dissertation reports on findings from three seasons of archaeological fieldwork at Pataraya, a mid-elevation site located on the western slope of the Andes in southern Peru, and its environs. These investigations began with large-scale excavations at Pataraya that were undertaken in 2007. While small, the site is an excellent example of the planned architectural style associated with the imperial expansion of the Wari state that emerged near modern-day Ayacucho during the Middle Horizon AD 750 – 1000). Intensive archaeological survey in the upland headwater valleys of the Nasca drainage was undertaken in 2008 and 2009. Two Middle Horizon sites, including another Wari compound known as Incawasi, were documented in the upper Aja river valley during these efforts and subsequent test excavations were undertaken at each of them in 2009. These surveys also collected data on a prehispanic road that connects the Nasca valley to the sierra. The road has been found to enter the Nasca drainage near modern-day Uchuymarca and travel past Incawasi and Pataraya on its route to the coastal plain below. These data strongly suggest that construction of the road dates to the Middle Horizon and that linkage of important Wari political installations was its primary function. Evidence from the excavations at Pataraya, especially when considered in light of this wider regional system, illuminate the organization and political economy of the Wari empire specifically, as well as the archaeological study of empires more broadly. The evidence from Pataraya suggests that activities related to textile manufacturing was a major part of daily life at the site. Given the importance of cotton in Wari textile technology and the Nasca valleys suitability for cultivation of the fiber, these data suggest that acquisition of coastal cotton and transshipment of the product to the sierra may have been one of the goals of the Wari state in establishing a colony at Pataraya. Wari control of the connection between the south coast and the sierra evidenced by both Pataraya and the newly discovered site of Incawasi also illuminates our understanding of the factors that direct investment in infrastructure by empires generally by demonstrating that many factors, some of which remain unknown, drove such heavy Wari investment in building a secure route to Nasca. Why empires invest heavily in one area and little or not at all in another is thus always an empirical question, one that must be evaluated and explained by real economic, environmental, political, and cultural conditions in the past.