316 economy: The Americas The Cahokian culture essentially evaporated by about the end of the 14th century No one is certain why, but historians offer a number of theories Chief among them is environmental degradation, warfare, or some combination of the two The Cahokians built a stockade around the city in about 1100, suggesting that some of their neighbors were not on entirely friendly terms with them Then, as the population grew, resources became scarcer Small increases in the water level of the surrounding rivers could have made large portions of cropland unusable The Cahokians consumed vast quantities of wood not only for firewood but also for the construction of structures, including the stockade, which periodically had to be rebuilt; just the stockade consumed about 20,000 relatively large trees Deforestation caused soil erosion, further reducing the amount of tillable land available to a growing population and creating marshlike conditions in many places along the rivers People had to go farther and farther away to find firewood, and game animals became scarcer At the same time, buffalo herds began to appear to the west, perhaps luring people away from the crowded city to the plains, where meat was plentiful—much as modern-day people move in response to changes in the labor market, housing prices, and similar economic factors Other Mississippian cultures up and down the river were becoming more powerful As a result of any or all of these factors, the economic system of the Cahokians collapsed, taking with it the entire population Mesoamerica Economic patterns in Mesoamerica continued those established during the ancient period Mesoamerica was inhabited by a succession of large and powerful city-states that relied on agriculture and trade for survival These cultures also left behind a considerable amount of monumental architecture Numerous civilizations from Mesoamerica could be cited, but perhaps the most dominant one during the pre-Columbian period was that of the Maya The reach of the Mayan civilization extended throughout northern Central America It included modern-day Guatemala, Belize, and parts of El Salvador and Honduras as well as the Mexican states of Tabasco, Chiapas, and, on the Yucatán Peninsula, Yucatán, Campeche, and Quintana Roo Historians conventionally divide Mayan history into three periods The earliest, the Preclassic, extended back into the centuries before the Common Era until about 250 c.e During the Classic Period, from about 250 to 900, Mayan civilization reached its zenith Sometime around 900 Mayan civilization went into decline and eventually collapsed Its position as the dominant Mesoamerican culture would later be assumed by the Aztec, the people the Black limestone mask, Santiago Ahuizotla, Mexico, 150 b.c.e to 700 c.e.; masks like this one, in the Teotihuacán style, were brought to the Aztec capital as tribute after wars. (© The Trustees of the British Museum) Spanish conquistadors encountered on their voyages to the New World in the 16th century The Mayan Classic Period was a period of intense economic activity Mayan culture was highly urbanized, with major cities including Palenque, Calakmul, Chichén Itzá, Caracol, Copán, and smaller cities including Bonampak, Altun Ha, Dos Pilas, and Uaxactun Most of these cities were located in the southern lowlands, though there were some population centers in the northern highlands One of the Maya’s most significant economic activities was pyramid construction For example, Calakmul is the site of the largest pyramid platform, at almost 150 feet squared, to have survived from the Classic Period, but numerous other pyramids, used primarily for ceremonial purposes, are found throughout the region Additionally, the Maya produced an extraordinary number of temples, administrative buildings, palaces, monuments, and stone slabs celebrating the lives of rulers Unfortunately, many of these buildings and monuments were made of soft, chalky limestone, so time has not been kind to them Mayan society was highly stratified, with a king at the top, a relatively small number of clan rulers, and a large peas-