There are only scant historical references to the Mazahua, relating mainly to their subordinate relationships to other groups. In one hypothesis about their background, they are believed to have formed part of the five tribes that made up Chichimec migrations to the Valley of Mexico. It is thought that they, together with the Matlazincas and Tlahuicas, were the founders of the cities of Culhuacan, Otompan, and Tula. According to another version, the Mazahua were one of the Acolhua groups that arrived in the Valley of Mexico around the twelfth century, along with the Otomí, their linguistic relatives. The Mazahua were soon subjugated by the Tecpanecs; nonetheless, their numerical superiority increased. Once Aztec rule was consolidated, the Mazahua came under their control, and their villages marked the borders with Michoacán. Among the most important cities of the Mazahua province of Mazahuacán were Azcapotzalco, Tenayocan (Tenayuca), Temazcalcingo, Atlacomulco, Chiapan, Xiquipilco, Xocotitlán, Malacatepec, and Ixtlahuaca. During the colonial period, the Mazahua occupied more or less the same habitat, but their subjugation was even more onerous than before. The system of tribute and slavery continued: the encomienda and later the repartimiento provided the colonists access to forced indigenous labor. The concentration of land in haciendas, the development of mining, and the establishment of manufacturing workshops were colonial means of economic subjugation. After the independence of Mexico in 1810, the situation of the Mazahua did not improve because this was a period when large haciendas were consolidated, and many Indians worked on them as peons. During the later Juárez reforms, the remaining communal lands belonging to indigenous communities were expropriated. They passed from the communal property system, which had protected them since colonial times, into the hands of large estate owners. It was only after the Mexican Revolution of 1910 that land was returned to indigenous peoples, in the form of ejidos. The small amount of land apportioned to each Mazahua family during the agrarian reforms of the 1930s set the stage for a mixed economy in which they were simultaneously producers of basic subsistence foodstuffs, consumers of industrially produced products, and sources of low-paid seasonal labor in the cities and on farms and cattle ranches.