In a unique political structure, each of the three allies headed a group of kingdoms in the core of the Empire. Each capital possessed settlements of peasants both in its own domain and in those of the other two capitals; in conquered areas nearby, the three capitals had their separate tributaries. Beyond the core, the Tenochca Empire conquered extensive regions from the Gulf Coast to the Pacific.
The Empire imposed a system of political control and tribute collection, with set amounts of the tribute going to each of the three great kingdoms. Though local rulers usually remained in the conquered areas, the empirical tribute collectors and other envoys frequently intervened in local affairs. The Empire also sent settlers to establish military colonies in the newly conquered regions.
In The Tenochca Empire Pedro Carrasco incorporates years of research in the archives of Mexico and Spain and compares primary sources, some not yet published, from all three of the great kingdoms. Carrasco goes beyond cataloging and locating conquests and tributary towns. He takes in the total tripartite structure of the Empire, defining its component entities and determining how they were organized and how they functioned.