and socioeconomic processes. In field exercises for classes at the National School of Anthropology, he organized a project at Xochicalco on the gulf, including one of the first settlement pattern studies in Mesoamerica (Sanders 1956).

The theoretical propositions of Armillas caused long-standing debates concerning the criteria for defining the concepts of state and civilization. Armillas proposed that urbanism is the key factor and that the great highland cities, especially Teotihuacán, constituted the principal centers of culture evolution in Mesoamerica. Other archaeologists, especially Caso and Bernal, contended that cultures outside the highlands, such as the Olmec and the Maya, played even more important roles in the evolution of Mesoamerican civilization than did the Teotihuacán (Sanders and Price 1968).

In contrast to earlier periods, various 1940s projects consisted of regional studies with objectives that went beyond merely establishing local cultural chronologies. At the beginning of the decade, Alberto Ruz Lhullier did a survey of the Campeche coast that in some ways was a precursor of later settlement pattern investigations. During the late 1940s, Ruz began a program at Palenque that produced important findings, including the 1952 discovery of the royal tomb in the Temple of the Inscriptions.

In 1943, the Carnegie Institution published an excellent report by Rubbert and Denisson of surveys in the jungles of Campeche, Quintana Roo, and the Petén of Guatemala, discovering important centers including El Mirador. During the same period, Pollock did an encyclopedic survey of Maya architecture in central Yucatán, especially in the Puuc area (Pollock 1980).

Other areas of Mexico began to be studied systematically: Rubin de la Borbolla, Moedano, Porter, and Estrada Balmori conducted a series of surveys and excavations in Guanajuato and Michoacán, especially in the regions of Chupicuaro, Tzintzuntzan, and Zinapécuaro, in which they investigated sites of many different periods. Corona Núñez (1942, 1946) studied Tarascan sites at this time, and Isabel Kelly studied numerous regions in western Mexico, especially in Michoacán, Jalisco, Sinaloa, and Colima (Kelly 1945–1949, 1980).

In 1944, Ekholm presented a detailed study of cultural sequences in the Huasteca of the northern Gulf coast, and his work is the source for the chronological framework that is still being used for this region. During the 1940s and 1950s, José García Payón directed key investigations in north-central Veracruz and eastern Puebla surveying major regions and excavating many sites, including El Tajin, Misantla, Zempoala, Castillo de Teayo, and Xiutetelco.

An important interdisciplinary project was organized by Espejo, Barlow, Griffin, and Franco at Tlatelolco in the basin of Mexico in which they attempted to correlate ethnohistorical reconstructions and events with archaeological data. Griffin and Espejo (1947, 1950) defined four general complexes of Aztec ceramics that became fundamental components of most late pre-Hispanic chronologies for central Mexico. At San Cristóbal Ecatepec in the northern basin, Du Solier (1947–1948) made thorough excavations of a long series of occupations from the late formative period (500 b.c.) until the Spanish conquest in the sixteenth century.

Also during the 1940s, several investigations of Pleistocene early hunters began. The discovery of an apparently very early human burial at Tepexpán (near Teotihuacán) by De Terra (1946) was followed by Aveleyra’s (1952) more reliable find of stone tools associated with a mammoth kill at Santa Isabel Ixtapan. Several other early sites were investigated, and by 1950, there was sufficient information for Aveleyra to write a book on the prehistory of Mexico. In 1952, the Department of Prehistory of the National Institute of Anthropology was founded with Pablo Martinez del Rio as its first director.

The National School of Anthropology, the key institution for archaeological teaching and investigation, was founded in 1937. During the 1940s and 1950s this school was one of the best places to study anthropology. The students came from many countries in the Americas and Europe, and the distinguished faculty included Wigberto Jiménez Moreno, Paul Kirchhoff, Pedro Armillas, Pedro Bosch Gimpera, Juan Comas, Miguel Covarrubias, Calixtla Guittierrez Holmes, Barbro Dahlgren, Roberto Weitlaner, Javier Romero, and Pablo Martínez del Rio.