In Tiwanaku levels at Qillqatani there is a notable decline in the use of obsidian, and of the two specimens analyzed one was of the local low-quality Aconcahua type and the other was Chivay.XFigure 3-7Xreveals that there is a reduction in the percentage of obsidian in the assemblage from this level. In the "debris" category, obsidian falls below 10% for the first time since the Middle Archaic Period. Ceramics were clearly Tiwanaku influenced, but they were relatively poorly made (Aldenderfer in prep.). One may speculate that with the establishment of Tiwanaku colonies in Moquegua, the dominant caravan traffic patterns shifted to an east-west pattern in the Qillqatani area. It is also possible that if the Tiwanaku economic sphere was dominating the circulation of Chivay obsidian, then the material would probably have been conveyed more directly into the Basin and the western cordillera exchange would have been relatively diminished.