of codices, religions, and calendars are classics (Coe 1993). Seler made numerous field trips to Mexico and Central America and published descriptions of sites and monuments in regions as diverse as guatemala, Chiapas, Oaxaca, Los Tuxtlas (Veracruz), and Zacatecas, among others. His study of the areas influenced by the major city of Teotihuacán, based mainly on the analysis of museum collections, was the direct precursor for the concepts of cultural unity that would be used to define Mesoamerica (Bernal 1979, 142). Seler knew several of the major pre-Hispanic languages and also made key contributions in ethnology and ethnohistory.

The Expansion of Mexican Archaeology

In 1911, at the beginning of the armed conflicts of the Mexican Revolution, the Escuela Internacional de Arqueología y Etnografía Americana (International School of American Archaeology and Ethnography) was founded in Mexico City. On the basis of agreements between the Mexican government and universities and museums in Germany, France, and the United States, the school functioned as a research institute. Even though it existed formally only until 1920, the institute’s activities were of such importance that its foundation clearly marked a new period in the development of Mexican archaeology. Directors included some of the greatest anthropologists in the Americas—Eduard Seler, Franz Boas, Alfred Tozzer, and manuel gamio—and the programs were truly anthropological, with important studies in ethnology and linguistics in various regions of Mexico, despite the violence of the revolution (Rivermar 1987). Heroic linguistic investigation was done by Boas (1917) in studying speakers of archaic Nahuatl (the language spoken by the Aztecs) in the remote Oaxaca coastal town of Pochutla, but such work may have been routine for a man who was studying the Eskimos of central Greenland in the 1880s.

The school’s central contribution to archaeology was the introduction of stratigraphic excavations in Mexico. In 1912, Gamio conducted a series of stratigraphic excavations at San Miguel Amantla (Azcapotzalco), which provided the basis for the first ancient culture sequence in the basin of Mexico. Boas and Gamio also extensively studied the collections of the national museum from sites in the basin of Mexico and published a catalog based on this work. Tozzer excavated Teotihuacán-period residences at Santiago Ahuizotla in the west-central basin near Azcapotzalco and identified a new ceramic complex called Coyotlatelco. It was eventually shown that this complex was part of a cultural tradition that appeared between the collapse of the Teotihuacán state and the rise of the Tula.

The sequence for the basin of Mexico proposed by the members of the International School consisted of three different cultures: archaic (which is now called formative), Toltec (related to the culture of Teotihuacán), and aztec. This chronological framework was partially modified by Alfred Kroeber in 1925, and in 1938, George Vaillant, on the basis of numerous stratigraphic excavations, published a more detailed chronology. The cultural sequence for the basin that is currently used was formulated by Pedro Armillas in 1950 on the basis of excavations at Teotihuacán along with the investigations of Vaillant and Sigvald Linne and the work of Acosta at Tula. Despite these modifications, it is fair to state that the investigations of the International School correctly identified the principal cultures of the basin of Mexico in the proper chronological order.

The outstanding figure in Mexican archaeology during the revolution and the decade of the 1920s was Manuel Gamio (González Gamio 1987), who had been one of Boas’s students at Columbia University in 1910–1911. Gamio was the last director of the International School, and between 1917 and 1922, supported by funds from the Mexican government, he planned and directed the first multidisciplinary anthropological project in the Americas on the population of the Teotihuacán Valley. The program comprised archaeology, ethnography, demography, geology, and environmental and agricultural studies and investigated the people of the Teotihuacán Valley from pre-Hispanic times to the twentieth century. The project’s findings were published in five volumes, and it was one of the most successful large-scale anthropological projects ever attempted, with a very advanced level of research for its time. The project’s most important