Starting at the end of the eighteenth century and continuing up to the present, explorers have searched for the ruins of ancient Mesoamerica, a region that includes Central America and central and southern Mexico. With the progress of time, archaeologists have unearthed civilizations increasingly remote in age. It is as if with each new century in the modern era an earlier stratum of antiquity has been revealed. Nineteenth-century explorers, particularly John Lloyd Stephens and Frederick Catherwood, came upon Maya cities in the jungle, as well as evidence of other Classic cultures. Twentieth-century research revealed a much earlier high civilization, the Olmec. It now scarcely seems possible that the frontiers of early Mesoamerican civilization can be pushed back any further, although new work – such as in Oaxaca, southern Mexico – will continue to fill in details of the picture. The process of discovery often shapes what we know about the history of Mesoamerican art. New finds are just as often made accidentally as intentionally. In 1971 workers installing sound and light equipment under the Pyramid of the Sun at Teotihuacan stumbled upon a remarkable cave that has since been interpreted by some scholars as a royal burial chamber. Archaeology has its own fashions too: the isolation of new sites may be the prime goal in one decade and the excavation of pyramids the focus in the next. In a third decade, outlying structures rather than principal buildings may absorb archaeologists' energies. Nor should one forget that excavators are vulnerable to local interests. At one point, reconstruction of pyramids to attract tourism may be desired; at another, archaeologists may be precluded from working at what has already become a tourist attraction. Also, modern construction often determines which ancient sites can be excavated. In Mexico City, for example, the building of the subway initiated the excavations there and renewed interest in the old Aztec capital. But the study of Mesoamerican art is not based exclusively on archaeology. Much useful information about the native populations was written down in the sixteenth century, particularly in central Mexico, and it can help us unravel the pre-Columbian past (the time prior to the arrival of Columbus in the Americas in 1492). Although many sources exist, the single most important one to the art historian is Bernardino de Sahagún's General History of the Things of New Spain. A Franciscan friar (member of the Roman Catholic religious order), Sahagún recorded for posterity many aspects of pre-Hispanic life in his encyclopedia of twelve books, including history, ideology, and cosmogony (theories of the origin of the universe), as well as detailed information on the materials and methods of the skilled native craft workers. Furthermore, traditional ways of life survive among the native peoples of Mesoamerica, and scholars have increasingly found that modern practice and belief can decode the past. Remarkably, some scholars have been turned this process around, teaching ancient writing to modern peoples who may use it to articulate their identity in the twenty-first century. During the past 40 years, scholars also have made great progress in deciphering and interpreting ancient Mesoamerican writing systems, a breakthrough that has transformed our understanding of the pre-Columbian mind. Classic Maya inscriptions, for example – long thought to record only calendrical information and astrological incantations – can now be read, and we find that most of them glorify family and ancestry by displaying the right of individual sovereigns to rule. The carvings can thus be seen as portraits or public records of dynastic power. Although scholars long believed that Mesoamerican artists did not sign their works, Mayanist scholar David Stuart's 1986 deciphering of the Maya glyphs (written symbols) for "scribe" and "to write" opened a window on Maya practice; now we know at least one painter of ceramic vessels was the son of a king. Knowledge of the minor arts has also come in large part through an active art market. Thousands more small-scale objects are known now than in the twentieth century, although at a terrible cost to the ancient ruins from which they have been plundered.