Obsidian in the Valley of Volcanoes, Peru

The Andagua Valley in the Department of Arequipa of southern Peru has only recently seen systematic archaeological investigations, revealing ancient agricultural communities that, despite apparent geographic isolation, were integrated economically with the wider Andean world. Portable x-ray fluorescence analysis of 137 obsidian artifacts recovered from sites in the lower Andagua Valley identifies the transfer of obsidian from Peru's three largest sources, with > 90% of the analyzed artifacts coming from the Alca-1 source northwest of the valley. In addition to Alca-1 obsidian, small amounts of obsidian from the distant sources of Chivay and Quispisisa appeared in distinct contexts associated with local pre-Inka occupations, corresponding with the Middle Horizon and Late Intermediate Periods (600 - 1000 and 1000 - 1400 Common Era). Obsidian from the Alca-4 and Alca-5 sources, originating on the adjacent plateau, was also transported to Andagua during these periods, possibly continuing under Inka imperial expansion after 1400 CE.Because there is no archaeological evidence of either Wari or Tiwanaku states in the lower Andagua Valley, the probable mechanisms of obsidian transfer include direct or down-the-line exchange between plateau-based camelid pastoralists and valley farmers. Therefore, at least some long-distance obsidian transfers in southern Peru were carried out without direct oversight from Wari or Tiwanaku, though these transfers may have been facilitated by region-scale economic integration during the Middle Horizon and Late Intermediate Period. Tracing the distribution of obsidian in the Andagua Valley highlights both intra-valley and inter-zonal relationships between the Valley of the Volcanoes and specific areas of the high-elevation Andean plateau while illuminating dynamic economic and social connections along the central Andes in the pre-Hispanic past.