The pre-Incan state of Tiwanaku (ca. AD 500–1100) spanned a large portion of the South American Andes with varying degrees of connection to the different regions. Through the use of strontium isotope analysis of skeletal remains, this paper examines the nature of Tiwanaku state expansion into the Cochabamba Valley of central Bolivia. Migration histories are reconstructed for a sample (n = 6) of individuals recovered from the site of Piñami in the Cochabamba Valley to determine the nature and degree of cultural interaction during the establishment of the Tiwanaku state. In revealing patterns of human mobility for a possible provincial territory, hypotheses are tested about the nature of the Tiwanaku polity and how it integrated outlying territories into its area of influence. Results from this preliminary study indicate that this small sample of the burial population was comprised predominantly (67%) of local inhabitants rather than migrants from the Tiwanaku heartland or another regional community. The relative abundance of Tiwanaku material culture paired with a disproportionate population of Tiwanaku migrants within the community supports existing research that Piñami was connected to the highland polity in a notable but likely non-hegemonic manner. Furthermore, the data may reveal a broader level of regional interaction occurring at Piñami with the presence of an individual from a separate outlying region. While this is a small sample, these findings offer a more nuanced understanding of Tiwanaku state expansion and integration during the prehistoric Middle Horizon in Bolivia, and contribute to a broader knowledge on prehistoric human migration and interaction in the south-central Andes.