The most important political entity in pre-Spanish Mesoamerica was the Tenochca Empire, founded in 1428 when the three kingdoms of Tenochtitlan, Tetzcoco, and Tlacopan formed an alliance that controlled the Basin of Mexico and other extensive areas of Mesoamerica. 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. 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 takes in the total tripartite structure of the Empire, defining its component entities and determining how they were organized and how they functioned.