Research in Peru’s Mantaro Valley is featured in the earliest published work of archaeologist Luis Guillermo Lumbreras. The developing elucidation of the archaeology of the Jauja-Huancayo area is employed in this paper as a way of tracing some of the origins of the major intellectual facets that later characterized Lumbreras’ contributions to Andean research. To set the stage for this appreciation, we need to understand the state of knowledge of the area when Lumbreras began his work there in 1956. As a subset of this background, the work of Federico Gálvez Durand is reviewed, because it provided a significant early resource base upon which, I argue, Lumbreras began to develop some of his subsequent intellectual interests. Following this, the argument turns to the specific themes that Lumbreras began developing, whose roots we can first detect emerging from his Mantaro Valley work, and focuses more intensely on the first decade or so of Lumbreras’ intellectual contributions, as appreciated from the perspective of Junin.