Chiapas, officially the Free and Sovereign State of Chiapas, is one of the states that make up the 32 federal entities of Mexico. It comprises 124 municipalities as of September 2017^[update] and its capital and largest city is Tuxtla Gutiérrez. Other important population centers in Chiapas include Ocosingo, Tapachula, San Cristóbal de las Casas, Comitán, and Arriaga. Chiapas is the southernmost state in Mexico, and it borders the states of Oaxaca to the west, Veracruz to the northwest, and Tabasco to the north, and the Petén, Quiché, Huehuetenango, and San Marcos departments of Guatemala to the east and southeast. Chiapas has a significant coastline on the Pacific Ocean to the southwest.

In general, Chiapas has a humid, tropical climate. In the northern area bordering Tabasco, near Teapa, rainfall can average more than 3,000 mm (120 in) per year. In the past, natural vegetation in this region was lowland, tall perennial rainforest, but this vegetation has been almost completely cleared to allow agriculture and ranching. Rainfall decreases moving towards the Pacific Ocean, but it is still abundant enough to allow the farming of bananas and many other tropical crops near Tapachula. On the several parallel sierras or mountain ranges running along the center of Chiapas, the climate can be quite moderate and foggy, allowing the development of cloud forests like those of Reserva de la Biosfera El Triunfo, home to a handful of horned guans, resplendent quetzals, and azure-rumped tanagers.

Chiapas is home to the ancient Mayan ruins of Palenque, Yaxchilán, Bonampak, Lacanha, Chinkultic, El Lagartero and Toniná. It is also home to one of the largest indigenous populations in the country, with twelve federally recognized ethnicities.

The official name of the state is Chiapas, which is believed to have come from the ancient city of Chiapan, which in Náhuatl means "the place where the chia sage grows." After the Spanish arrived (1522), they established two cities called Chiapas de los Indios and Chiapas de los Españoles (1528), with the name of Provincia de Chiapas for the area around the cities. The first coat of arms of the region dates from 1535 as that of the Ciudad Real (San Cristóbal de las Casas). Chiapas painter Javier Vargas Ballinas designed the modern coat of arms.^{[need quotation to verify]}

Hunter gatherers began to occupy the central valley of the state around 7000 BCE, but little is known about them. In the pre Classic period from 1800 BCE to 300 CE, agricultural villages appeared all over the state although hunter gather groups would persist for long after the era.

Recent excavations in the Soconusco region of the state indicate that the oldest civilization to appear in what is now modern Chiapas is that of the Mokaya, which were cultivating corn and living in houses as early as 1500 BCE, making them one of the oldest in Mesoamerica. There is speculation that these were the forefathers of the Olmec, migrating across the Grijalva Valley and onto the coastal plain of the Gulf of Mexico to the north, which was Olmec territory. The descendants of Mokaya are the Mixe-Zoque. During the pre Classic era, it is known that most of Chiapas was not Olmec, but had close relations with them, especially the Olmecs of the Isthmus of Tehuantepec.

Mayan civilization began in the pre-Classic period as well, but did not come into prominence until the Classic period (300–900 CE). Development of this culture was agricultural villages during the pre-Classic period with city building during the Classic as social stratification became more complex. In Chiapas, Mayan sites are mostly concentrated along the state's borders with Tabasco and Guatemala, near Mayan sites in those entities. Most of this area belongs to the Lacandon Jungle. Mayan civilization in the Lacandon area is marked by rising exploitation of rain forest resources, rigid social stratification, fervent local identity, waging war against neighboring peoples. At its height, it had large cities, a writing system, and development of scientific knowledge, such as mathematics and astronomy.

It is not known what ended the Mayan civilization but theories range from over population size, natural disasters, disease, and loss of natural resources through over exploitation or climate change. Nearly all Mayan cities collapsed around the same time, 900 CE. From then until 1500 CE, social organization of the region fragmented into much smaller units and social structure became much less complex. There was some influence from the rising powers of central Mexico but two main indigenous groups emerged during this time, the Zoques and the various Mayan descendants. The Chiapans, for whom the state is named, migrated into the center of the state during this time and settled around Chiapa de Corzo, the old Mixe–Zoque stronghold. There is evidence that the Aztecs appeared in the center of the state around Chiapa de Corza in the 15th century, but were unable to displace the native Chiapa tribe. However, they had enough influence so that the name of this area and of the state would come from Nahuatl.