The state is one of the smallest in Mexico, but it is also one of the most heterogeneous geographically, with ecosystems varying from deserts to tropical rainforest, especially in the Sierra Gorda, which is filled with microecosystems. The area of the state was located on the northern edge of Mesoamerica, with both the Purépecha Empire and Aztec Empire having influence in the extreme south, but neither really dominating it. The area, especially the Sierra Gorda, had a number of small city-states, but by the time the Spanish arrived, these had all been abandoned, with only small agricultural villages and seminomadic peoples inhabiting the area. Spanish conquest was focused on the establishment of the Santiago de Querétaro, which still dominates the state culturally, economically and educationally.