The earliest mentions of Sierra Nahuat settlements appear in post-Conquest reconstructions of Aztec history referring to the extension of the tribute empire of Moctezuma I (1440-1468) into what is now known as the northern Sierra de Puebla. The Sierra Nahuat contributed maize, beans, and cotton and provided men for Aztec armies fighting the Nahuatl of Tlaxcala. Hernán Cortéz apparently passed through the region on his way to the Valley of Mexico early in the sixteenth century, but Spaniards did not settle in the region until late in the next century. The first settlers, who opened mines in Tetela de Ocampo, Tlatlauquitepec, and Teziutlán, were followed by cattle ranchers and farmers. With the development of railroads in the last decades of the nineteenth century, many Spanish-speaking Mexicans moved into lower-elevation Sierra Nahuat communities to grow sugarcane and coffee. Spanish and mestizo settlement created a number of biethnic communities with clearly defined Sierra Nahuat and Spanish-speaking populations organized into systems of ethnic stratification. Spanish-speaking Mexicans have taken the bulk of the land, with help from the Colonization laws of 1883 and 1894, which forced the Sierra Nahuat, who held land corporately, to adopt fee-simple tenure (ownership with unrestricted rights to dispose of the land) and register their land in the district capitals. Many could not prove ownership and lost their land in public sales or pawned it to Spanish-speaking merchants. Some regained less productive land as ejidos during the Agrarian Land Reform of the 1930s and 1940s, but changes made in Mexican law in 1992 create the possibility of converting ejidos into private property. Spanish-speaking Mexicans export the vast majority of cash crops (coffee, sugarcane, plums, apples, and avocados); occupy the most important state, regional, and municipio offices; and run many of the schools. Sierra Nahuat in the few monoethnic communities retain their land and run their municipio government.