The late manifestation of Tiwanaku affiliated culture in the upper Moquegua valley is known as Tumilaca which is associated with the terminal Middle Horizon (A.D. 950-1250). However, after A.D. 1250 radical changes in residential space, material culture and mortuary practices are associated with the Estuquiña phase. This thesis study analyzes diet in archaeological human remains through carbon (δ¹³C_collagen & δ¹³C_carbonate), nitrogen (δ¹⁵N_collagen), and oxygen (δ¹⁸O_carbonate) isotopic values between Tumilaca and Estuquiña groups at the site of Tumilaca la Chimba in the upper Moquegua valley. Carbon (δ¹³C_carbonate) and Oxygen (δ¹⁸O_carbonate) isotopic values indicated high consumption of C₃ plants and same local water consumption in both Tumilaca and Estuquiña populations. Meanwhile, Carbon and nitrogen isotope values (δ¹³C_collagen vs. δ¹⁵N_collagen) evidenced low consumption of C₄ plants (maize) but high local terrestrial C₃ plants and animal meat sources. The low evidence of maize consumption in the upper Moquegua valley could be linked to Tiwanaku collapse.