Current evidence suggests that following the collapse of the Tiwanaku state, a prolonged drought occurred until AD1200 after which time Aymara chiefdoms emerged in the region referred to as Collasuyu by the Inka. A central question of this time period concerns the extent to which obsidian distributions can reveal whether Tiwanaku period interaction patterns persisted into the LIP in the forms assumed by economic organization and long distance exchange. While the LIP is known as the auca runaor the "time of strife" when fortified hilltop refuges " pukaras"were constructed in abundance in the Titicaca Basin and adjacent territories, the weapons used in these conflicts appear to have primarily been percussion weapons like slings and clubs, and not obsidian tipped-projectiles.
In a review that considers the LIP and Late Horizon together in one discussion, Burger et al.(2000)note the declining presence of obsidian in most LIP and LH contexts in the region. Many of the chemically provenienced obsidian samples from the Titicaca Basin come from surface contexts with either LH or LIP associations, and the pattern revealed in the Titicaca Basin from these samples is one of almost exclusive use of Chivay type material. One of the reasons for the strong presence of Chivay obsidian over Alca obsidian may have resulted from cultural affinities between Aymara groups(Browman 1994). The Colla in the North Titicaca Basin and the Collagua in the upper Colca area share many traits including the construction of pukaras(Wernke 2003: 262-263), mortuary features including chulpaburial structures and fiber-wrapped mummy encasings(de la Vega, et al. 2005;Wernke 2003: 225-234), and other commonalities.
In the northern Lake Titicaca Basin, Arkush(2005: 247)notes that two-thirds of the occupied pukaras throughout her survey area contained obsidian on the surface, and that chert flakes and blades are common. In one instance, at Calvario de Asillo (AS1) prepared obsidian cores and a concentration of flakes was encountered. Obsidian projectile points were small, triangular base-notched points (series 5), consistent with the Klink and Aldenderfer point typology for the Terminal Archaic and onwards(Arkush 2005: 709-711). Metal objects are common as well, with copper and copper-alloy pendants and tupus(long pins) frequently found at pukaras.
Six obsidian samples from the mesa-top pukaraand chulpaburial tower complex of Cutimbo were analyzed by Frye et al.(1998)and the samples were 100% from the Chivay source. Burger et al.(2000: 343-344)indicate that one obsidian sample from the renowned chulpacomplex of Sillustani was also from the Chivay source. Burger et al. observe that while a single Alca flake was excavated at Taraco from an LIP context, and another was found on the surface at the LIP or LH site of Kolkeparke near Ayaviri(Burger, et al. 2000: 343), the Titicaca Basin is otherwise entirely supplied from the Chivay source during the LIP.
At the rock shelter of Qillqatani (SectionX3.4.2X) a large percentage (15.4%) of the tools from LIP levels were made from obsidian, although the count is very low (n = 2) and the tools were extremely small. The single obsidian sample that was analyzed proved to be from the Chivay source.
In the south-western Lake Titicaca area, Hyslop(1976: 118-119)found that the Lupaqa sites he encountered in the course of his road system survey contained primarily basalt and quartzite flaked stone. More recent survey work in the Ilave and Huenque drainages(Klink and Aldenderfer 1996)found that high-quality cherts are abundant in the region, which suggests that the prominent use of basalt at the sites Hyslop encountered was by choice, not by necessity, and was perhaps a reflection of lakeshore agricultural activities.