The Classic Maya Collapse refers to the decline and abandonment of the Classic Period Maya cities of the southern Maya lowlands of Mesoamerica between the 8th and 9th centuries. This should not be confused with the collapse of the Preclassic Maya in the 2nd century AD. The Classic Period of Mesoamerican chronology is generally defined as the period from AD 300 to 900, the last 100 years of which, from AD 800 to 900, are frequently referred to as the Terminal Classic. The Classic Maya Collapse is one of the biggest mysteries in archaeology. What makes this development so intriguing is the combination of the cultural sophistication attained by the Maya before the collapse and the relative suddenness of the collapse itself.
The highly advanced Maya centers of the southern lowlands went into decline during the 8th and 9th centuries and were abandoned shortly thereafter. Archaeologically, this decline is indicated by the cessation of monumental inscriptions and the reduction of large-scale architectural construction. A number of Maya cities, however, did not collapse, and Maya civilization continued until 1697 when the Spanish conquered Tayasal, the last independent city-state. In fact, after the "collapse," the Maya of the northern Yucat n prospered, and the Chichen Itza state built an empire that briefly united much of the Maya region. Because parts of Maya civilization unambiguously continued, a number of scholars strongly dislike the term "collapse." Regarding the proposed collapse, E. W. Andrews IV went as far as to say, "in my belief no such thing happened."
Some 88 different theories or variations of theories attempting to explain the Classic Maya Collapse have been identified. From climate change to deforestation to lack of action by Mayan kings, there is no universally accepted collapse theory, although drought is gaining momentum as the leading explanation.
The archaeological evidence of the Toltec intrusion into Yucat n in Seibal, Peten suggests to some the theory of foreign invasion. The latest hypothesis states that the southern lowlands were invaded by a non-Maya group whose homelands were probably in the gulf coast lowlands. This invasion began in 9th century and set off, within 100 years, a group of events that destroyed the Classic Maya. It is believed that this invasion was somehow influenced by the Toltec people of central Mexico. However, most Mayanists do not believe that foreign invasion was the main cause of the Classic Maya Collapse; they postulate that no military defeat can explain or be the cause of the protracted and complex Classic Collapse process. Teotihuacan influence across the Maya region may have involved some form of military invasion, however it is generally noted that significant Teotihuacan-Maya interactions date from at least the Early Classic period, well before the episodes of Late Classic collapse.
Dr Michel Peissel believes that the well documented conquest of Yucat n in the 9th century by the Chichen Itza polity, led to the rerouting along coastal sea routes of most of the (cacao) trade that used to transit through (and enrich) the major inland cities, which were ruined overnight, as were those of the silk road when Portuguese traders began to transfer silk by ship to Europe from China and Japan. Peissel's theory, validated by several scholars, explains why the collapse was not general and also why at the time of the collapse of lowland cities other towns flourished - most of them along the new routes opened up by the Chichen Itza maritime traders. To prove the feasibility of this transfer from overland trade routes to the sea, Dr Peissel with three Mexican archeologists and ten companions travelled 650 kilometers in 1988 on a sea-going Mayan dugout from Chunyache in Quintana Roo (Mexico) to the upper reaches of the Mojo River in Belize.
Peasant revolt, revolution, or social turmoil
Archaeological evidence indicates that Maya building and expansion projects were at their peak from c. 730 to 790 (specifically during the k'atun), with constant enlargement and building and without any machines or beneficial tools to assist them. During this same time period, signs foreshadowing the collapse of Maya civilizations were beginning to appear. The majority of the burden was placed on peasant workers in the cities, like Tikal and Copan, with a seemingly endless construction, making ball courts and other buildings bigger. One theory, supported by J. Eric S. Thompson, attributes the collapse of the classic Maya to a hypothesized revolution among these lower Maya social classes. As life became more burdensome, work began to "undermine the religious development and collective enterprise of ordinary people", according to this line of thinking. The increased burden of work may have caused people to abandon their values and revolt against the elite of society, specifically the priest-rulers, since the Maya were believed to be theocratic and thus ruled by the priests. This might help explain the abrupt collapse of elite functions, as well as unfinished buildings and ceremonial centers. Since the collapse of various civilizations occurred at various times, it is believed that the revolts of individual groups were a part of a unplanned and impulsive series. In the civilization of Piedras Negras (Maya site), for example, there seemed to be some sort of violence during this time period that was displayed through various palace buildings being set on fire and a throne being destroyed. While this seems to be a revolt between the peasants and the priests, the model being called the "priest-peasant" model, it was later discovered that kings ruled during the Pre Classic and Classic period within the Maya social classes rather than priests.
Even though these theories seemed to be a good explanation of the sudden collapse of the Maya civilizations, it still contains problems. First of all, Thompson's theory does not answer the question of where all the inhabitants went. David Webster believed that the population should have increased, instead of decreasing because of the lack of elite power. Second, it is not understood why the governmental institutions were not remade following the revolts, which actually happened under similar circumstances in places like China. Third, after a study was done by Elliot Abrams, he came to the conclusion that buildings, specifically in Copan, did not actually need the extensive amount of time and workers to complete the constructions. However, when Thompson had developed this theory, it was during a time period in which the archaeological evidence showed that there were fewer Maya people then as are now known. Revolutions, peasant revolts, and social turmoil change things, and often are followed by foreign wars, but they run their course. There are no documented revolutions that caused wholesale abandonment of entire regions.
Collapse of trade routes
It has been hypothesized that the decline of the Maya is related to the collapse of their intricate trade systems, especially those connected to the central Mexican city of Teotihuac n. Preceding improved knowledge of the chronology of Mesoamerica, Teotihuacan was believed to have fallen during AD 700 750, forcing the "restructuring of economic relations throughout highland Mesoamerica and the Gulf Coast". This remaking of relationships between civilizations would have then given the collapse of the Classic Maya a slightly later date. However, after knowing more about the events and the time periods that they occurred, it is now believed that the strongest Teotihuacan influence was during the 4th and 5th centuries. In addition, the civilization of Teotihuacan started to lose its power, and maybe even abandoned the city, during AD 600 650. This differs greatly from the previous belief that Teotihuacano power decreased during AD 700 750. But since the new decline date of AD 600 650 has been accepted, the Maya civilizations are now thought to have lived on, and also prospered for another century and more  than what was previously believed. Rather than the decline of Teotihuacan directly preceding the collapse of the Maya, their decline is now seen as contributing to the 6th century hiatus .
The disease theory is also a contender as a factor in the Classic Maya Collapse. Widespread disease could explain some rapid depopulation, both directly through the spread of infection itself and indirectly as an inhibition to recovery over the long run. According to Dunn (1968) and Shimkin (1973), infectious diseases spread by parasites are common in tropical rainforest regions, such as the Maya lowlands. Shimkin specifically suggests that the Maya may have encountered endemic infections related to American trypanosomiasis, Ascaris, and some enteropathogens that cause acute diarrheal illness. Furthermore, some experts believe that, through development of their civilization (that is, development of agriculture and settlements), the Maya could have created a "disturbed environment," in which parasitic and pathogen-carrying insects often thrive. Among the pathogens listed above, it is thought that those that cause the acute diarrheal illnesses would have been the most devastating to the Maya population. This is because such illness would have struck a victim at an early age, thereby hampering nutritional health and the natural growth and development of a child. This would have made them more susceptible to other diseases later in life. Such ideas as this could explain the role of disease as at least a possible partial reason for the Classic Maya Collapse.
Mega-droughts hit the Yucat n Peninsula and Pet n Basin areas with particular ferocity, for several reasons:
- Thin tropical soils, which decline in fertility and become unworkable when deprived of forest cover;
- Regular seasonal drought, drying up surface water;
The colonial Spanish officials accurately documented cycles of drought, famine, disease, and war, providing a reliable historical record of the basic drought pattern in the Maya region.
Climatic factors were first implicated in the Collapse as early as 1931 by Mayanists Thomas Gann and J.E.S. Thompson. In The Great Maya Droughts, Richardson Gill gathers and analyzes an array of climatic, historical, hydrologic, tree ring, volcanic, geologic, lake bed, and archeological research, and demonstrates that a prolonged series of droughts most likely caused the Classic Maya Collapse. The drought theory provides a comprehensive explanation, because non-environmental and cultural factors (excessive warfare, foreign invasion, peasant revolt, less trade, etc.) can all be explained by the effects of prolonged drought on Classic Maya civilization.
Climatic changes are, with increasing frequency, found to be major drivers in the rise and fall of civilizations all over the world. Professors Harvey Weiss of Yale University and Raymond S. Bradley of the University of Massachusetts have written: "Many lines of evidence now point to climate forcing as the primary agent in repeated social collapse." In a separate publication, Weiss illustrates an emerging understanding of scientists:
"Within the past five years new tools and new data for archaeologists, climatologists, and historians have brought us to the edge of a new era in the study of global and hemispheric climate change and its cultural impacts. The climate of the Holocene, previously assumed static, now displays a surprising dynamism, which has affected the agricultural bases of pre-industrial societies. The list of Holocene climate alterations and their socio-economic effects has rapidly become too complex for brief summary."
The drought theory holds that rapid climate change in the form of severe drought brought about the Classic Maya collapse. According to the particular version put forward by Gill in The Great Maya Droughts,
"[Studies of] Yucatecan lake sediment cores ... provide unambiguous evidence for a severe 200-year drought from AD 800 to 1000 ... the most severe in the last 7,000 years ... precisely at the time of the Maya Collapse."
Climatic modeling, tree ring data, and historical climate data show that cold weather in the Northern Hemisphere is associated with drought in Mesoamerica. Northern Europe suffered extremely low temperatures around the same time as the Maya droughts. The same connection between drought in the Maya areas and extreme cold in northern Europe was found again at the beginning of the 20th century. Volcanic activity, within and outside Mesoamerica, is also correlated with colder weather and resulting drought, as the effects of the Tambora volcano eruption in 1815 indicate.
Mesoamerican civilization provides a remarkable exception: civilization prospering in the tropical swampland. The Maya are often conceived as having lived in a rainforest, but technically, they lived in a seasonal desert without access to stable sources of drinking water. The exceptional accomplishments of the Maya are all the more remarkable because of their engineered response to the fundamental environmental difficulty of relying upon rainwater rather than permanent sources of water. The Maya succeeded in creating a civilization in a seasonal desert by creating a system of water storage and management which was totally dependent on consistent rainfall.  The constant need for water kept the Maya on the edge of survival. Given this precarious balance of wet and dry conditions, even a slight shift in the distribution of annual precipitation can have serious consequences. 
Water and civilization were vitally connected in ancient Mesoamerica. Archaeologist and specialist in pre-industrial land and water usage practices, Vernon Scarborough, believes water management and access were critical to the development of Maya civilization.
Critics of the drought theory wonder why the southern and central lowland cities were abandoned and the northern cities like Chichen Itza, Uxmal, and Coba continued to thrive. One critic argued that Chichen Itza revamped its political, military, religious, and economic institutions away from powerful lords or kings. Inhabitants of the northern Yucat n also had access to seafood, which might have explained the survival of Chichen Itza and Mayapan, cities away from the coast but within reach of coastal food supplies. Critics of the drought theory also point to current weather patterns: much heavier rainfall in the southern lowlands compared to the lighter amount of rain in the northern Yucat n. Drought theory supporters state that the entire regional climate changed, including the amount of rainfall, so that modern rainfall patterns are not indicative of rainfall from AD 800 to 900. LSU archaeologist Heather McKillop found a significant rise in sea level along the coast nearest the southern Maya lowlands, coinciding with the end of the Classic period, and indicating climate change.
David Webster, a critic of the megadrought theory says that much of the evidence provided by Gill comes from the northern Yucat n and not the Southern part of the peninsula, where Classic Maya civilization flourished. He also states that if water sources were to have dried up, then several city-states would have moved to other water sources. The fact that Gill suggests that all water in the region would have dried up and destroyed Maya civilization is a stretch, according to Webster.
A study published in Science in 2012 found that modest rainfall reductions, that amount to only 25 to 40 per cent in annual rainfall, may have been the tipping point to the Mayan collapse. Based on samples of lake and cave sediments in the areas surrounding major Mayan cities, the researchers were able to determine the amount of annual rainfall in the region. The mild droughts that took place between AD 800-950 were enough to rapidly deplete seasonal water supplies in the Yucatan lowlands, where there are no rivers.
Systemic ecological collapse model
Some ecological theories of Maya decline focus on the worsening agricultural and resource conditions in the late Classic period. It was originally thought that the majority of Maya agriculture was dependent on a simple slash-and-burn system. Based on this method, the hypothesis of soil exhaustion was advanced by Orator F. Cook in 1921. Similar soil exhaustion assumptions are associated with erosion, intensive agricultural, and savanna grass competition.
More recent investigations have shown a complicated variety of intensive agricultural techniques utilized by the Maya, explaining the high population of the Classic Maya polities. Modern archaeologists now comprehend the sophisticated intensive and productive agricultural techniques of the ancient Maya, and several of the Maya agricultural methods have not yet been reproduced. Intensive agricultural methods were developed and utilized by all the Mesoamerican cultures to boost their food production and give them a competitive advantage over less skillful peoples. These intensive agricultural methods included canals, terracing, raised fields, ridged fields, chinampas, the use of human faeces as fertilizer, seasonal swamps or bajos, using muck from the bajos to create fertile fields, dikes, dams, irrigation, water reservoirs, several types of water storage systems, hydraulic systems, swamp reclamation, swidden systems, and other agricultural techniques which have not yet been fully comprehended. Systemic ecological collapse is said to be evidenced by deforestation, siltation, and the decline of biological diversity.
In addition to mountainous terrain, Mesoamericans successfully exploited the very problematic tropical rainforest for 1,500 years. The agricultural techniques utilized by the Maya were entirely dependent upon ample supplies of water. The Maya thrived in what to most peoples would be uninhabitable territory. Their success over two millennia in this environment was "amazing."
Anthropologist Joseph Tainter wrote extensively about the collapse of the Southern Lowland Maya in his 1988 study, The Collapse of Complex Societies. His theory about Mayan collapse encompasses some of the above explanations, but focuses specifically on the development of and the declining marginal returns from the increasing social complexity of the competing Mayan city-states.
es:Colapso maya it:Collasso dei Maya mk: pt:Colapso maia fi:Klassisen mayakulttuurin romahdus