Maya civilization

Context: The Maya civilization developed within the Mesoamerican cultural area, which covers a region that spreads from northern Mexico southwards into Central America. Mesoamerica was one of six cradles of civilization worldwide. The Mesoamerican area gave rise to a series of cultural developments that included complex societies, agriculture, cities, monumental architecture, writing, and calendrical systems. The set of traits shared by Mesoamerican cultures also included astronomical knowledge, blood and human sacrifice, and a cosmovision that viewed the world as divided into four divisions aligned with the cardinal directions, each with different attributes, and a three-way division of the world into the celestial realm, the earth, and the underworld.  By 6000 BC, the early inhabitants of Mesoamerica were experimenting with the domestication of plants, a process that eventually led to the establishment of sedentary agricultural societies. The diverse climate allowed for wide variation in available crops, but all regions of Mesoamerica cultivated the base crops of maize, beans, and squashes. All Mesoamerican cultures used Stone Age technology; after c. 1000 AD copper, silver and gold were worked. Mesoamerica lacked draft animals, did not use the wheel, and possessed few domesticated animals; the principal means of transport was on foot or by canoe. Mesoamericans viewed the world as hostile and governed by unpredictable deities. The ritual Mesoamerican ballgame was widely played. Mesoamerica is linguistically diverse, with most languages falling within a small number of language families - the major families are Mayan, Mixe-Zoquean, Otomanguean, and Uto-Aztecan; there are also a number of smaller families and isolates. The Mesoamerican language area shares a number of important features, including widespread loanwords, and use of a vigesimal number system.  The territory of the Maya covered a third of Mesoamerica, and the Maya were engaged in a dynamic relationship with neighbouring cultures that included the Olmecs, Mixtecs, Teotihuacan, the Aztecs, and others. During the Early Classic period, the Maya cities of Tikal and Kaminaljuyu were key Maya foci in a network that extended beyond the Maya area into the highlands of central Mexico. At around the same time, there was a strong Maya presence at the Tetitla compound of Teotihuacan. Centuries later, during the 9th century AD, murals at Cacaxtla, another site in the central Mexican highlands, were painted in a Maya style. This may have been either an effort to align itself with the still-powerful Maya area after the collapse of Teotihuacan and ensuing political fragmentation in the Mexican Highlands, or an attempt to express a distant Maya origin of the inhabitants. The Maya city of Chichen Itza and the distant Toltec capital of Tula had an especially close relationship.  The Maya developed their first civilization in the Preclassic period. Scholars continue to discuss when this era of Maya civilization began. Maya occupation at Cuello (modern-day Belize) has been carbon dated to around 2600 BC. Settlements were established around 1800 BC in the Soconusco region of the Pacific coast, and the Maya were already cultivating the staple crops of maize, beans, squash, and chili pepper. This period was characterized by sedentary communities and the introduction of pottery and fired clay figurines.  During the Middle Preclassic Period, small villages began to grow to form cities. Nakbe in the Peten department of Guatemala is the earliest well-documented city in the Maya lowlands, where large structures have been dated to around 750 BC. The northern lowlands of Yucatan were widely settled by the Middle Preclassic. By approximately 400 BC, early Maya rulers were raising stelae. A developed script was already being used in Peten by the 3rd century BC. In the Late Preclassic Period, the enormous city of El Mirador grew to cover approximately 16 square kilometres (6.2 sq mi). Although not as large, Tikal was already a significant city by around 350 BC.  In the highlands, Kaminaljuyu emerged as a principal centre in the Late Preclassic. Takalik Abaj and Chocola were two of the most important cities on the Pacific coastal plain, and Komchen grew to become an important site in northern Yucatan. The Late Preclassic cultural florescence collapsed in the 1st century AD and many of the great Maya cities of the epoch were abandoned; the cause of this collapse is unknown.  Although much reduced, a significant Maya presence remained into the Postclassic period after the abandonment of the major Classic period cities; the population was particularly concentrated near permanent water sources. Unlike during previous cycles of contraction in the Maya region, abandoned lands were not quickly resettled in the Postclassic. Activity shifted to the northern lowlands and the Maya Highlands; this may have involved migration from the southern lowlands, because many Postclassic Maya groups had migration myths. Chichen Itza and its Puuc neighbours declined dramatically in the 11th century, and this may represent the final episode of Classic Period collapse. After the decline of Chichen Itza, the Maya region lacked a dominant power until the rise of the city of Mayapan in the 12th century. New cities arose near the Caribbean and Gulf coasts, and new trade networks were formed.  The Postclassic Period was marked by changes from the preceding Classic Period. The once-great city of Kaminaljuyu in the Valley of Guatemala was abandoned after continuous occupation of almost 2,000 years. Across the highlands and neighbouring Pacific coast, long-occupied cities in exposed locations were relocated, apparently due to a proliferation of warfare. Cities came to occupy more-easily defended hilltop locations surrounded by deep ravines, with ditch-and-wall defences sometimes supplementing the protection provided by the natural terrain. One of the most important cities in the Guatemalan Highlands at this time was Q'umarkaj, the capital of the aggressive K'iche' kingdom. The government of Maya states, from the Yucatan to the Guatemalan highlands, was often organized as joint rule by a council. However, in practice one member of the council could act as a supreme ruler, while the other members served him as advisors.  Mayapan was abandoned around 1448, after a period of political, social and environmental turbulence that in many ways echoed the Classic period collapse in the southern Maya region. The abandonment of the city was followed by a period of prolonged warfare, disease and natural disasters in the Yucatan Peninsula, which ended only shortly before Spanish contact in 1511. Even without a dominant regional capital, the early Spanish explorers reported wealthy coastal cities and thriving marketplaces. During the Late Postclassic, the Yucatan Peninsula was divided into a number of independent provinces that shared a common culture but varied in internal sociopolitical organization. On the eve of the Spanish conquest, the highlands of Guatemala were dominated by several powerful Maya states. The K'iche' had carved out a small empire covering a large part of the western Guatemalan Highlands and the neighbouring Pacific coastal plain. However, in the decades before the Spanish invasion the Kaqchikel kingdom had been steadily eroding the kingdom of the K'iche'. CANNOTANSWER

Question: What else in addition to the calendar did the Mayans develop during the Postclassic period??
Answer: During the Middle Preclassic Period, small villages began to grow to form cities.