The tropics are the region of the Earth surrounding the Equator. They are delimited in latitude by The Tropic of Cancer in the Northern Hemisphere at 23°26′12.4″ N and the Tropic of Capricorn in the Southern Hemisphere at 23°26′12.4″ S. The tropics are referred to as the tropical zone and the torrid zone; the tropics include all the areas on the Earth where the Sun contacts a point directly overhead at least once during the solar year - thus the latitude of the tropics is equal to the angle of the Earth's axial tilt. The tropics are distinguished from the other climatic and biomatic regions of Earth, which are the middle latitudes and the polar regions on either side of the equatorial zone; the tropics contain 36 % of the Earth's landmass. As of 2014, the region is home to 40% of the world population, this figure is projected to reach 50% by the late 2030s. "Tropical" is sometimes used in a general sense for a tropical climate to mean warm to hot and moist year-round with the sense of lush vegetation.
Many tropical areas have a wet season. The wet season, rainy season or green season is the time of year, ranging from one or more months, when most of the average annual rainfall in a region falls. Areas with wet seasons are disseminated across portions of the subtropics. Under the Köppen climate classification, for tropical climates, a wet-season month is defined as a month where average precipitation is 60 millimetres or more. Tropical rainforests technically do not have dry or wet seasons, since their rainfall is distributed through the year; some areas with pronounced rainy seasons see a break in rainfall during mid-season when the intertropical convergence zone or monsoon trough moves poleward of their location during the middle of the warm season. When the wet season occurs during the warm season, or summer, precipitation falls during the late afternoon and early evening hours; the wet season is a time when air quality improves, freshwater quality improves and vegetation grows leading to crop yields late in the season.
Floods cause rivers to overflow their banks, some animals to retreat to higher ground. Soil nutrients erosion increases; the incidence of malaria increases in areas. Animals have survival strategies for the wetter regime; the previous dry season leads to food shortages into the wet season, as the crops have yet to mature. However, regions within the tropics may well not have a tropical climate. Under the Köppen climate classification, much of the area within the geographical tropics is classed not as "tropical" but as "dry", including the Sahara Desert, the Atacama Desert and Australian Outback. There are alpine tundra and snow-capped peaks, including Mauna Kea, Mount Kilimanjaro, the Andes as far south as the northernmost parts of Chile and Argentina. Tropical plants and animals are those species native to the tropics. Tropical ecosystems may consist of tropical rainforests, seasonal tropical forests, dry forests, spiny forests and other habitat types. There are significant areas of biodiversity, species endemism present in rainforests and seasonal forests.
Some examples of important biodiversity and high endemism ecosystems are El Yunque National Forest in Puerto Rico, Costa Rican and Nicaraguan rainforests, Amazon Rainforest territories of several South American countries, Madagascar dry deciduous forests, the Waterberg Biosphere of South Africa, eastern Madagascar rainforests. The soils of tropical forests are low in nutrient content, making them quite vulnerable to slash-and-burn deforestation techniques, which are sometimes an element of shifting cultivation agricultural systems. In biogeography, the tropics are divided into Neotropics. Together, they are sometimes referred to as the Pantropic; the Neotropical region should not be confused with the ecozone of the same name. "Tropicality" refers to the geographic imagery that many people outside the tropics have of that region. The idea of tropicality gained renewed interest in modern geographical discourse when French geographer Pierre Gourou published Les Pays Tropicaux, in the late 1940s.
Tropicality encompasses at least two contradictory imageries. One is that the tropics represent a Garden of a heaven on Earth; the latter view was discussed in Western literature—more so than the first. Evidence suggests that over time the more primitive view of the tropics in popular literature has been supplanted by more nuanced interpretations that reflect historical changes in values associated with tropical culture and ecology, although some primitive associations are persistent. Western scholars theorized about the reasons that tropical areas were deemed "inferior" to regions in the Northern Hemisphere. A popular explanation focused on the differences in climate—tropical regions have much warmer weather than northern regions; this theme led some scholars, including Gourou, to argue that warmer climates correlate to primitive indigenous populations lacking control over nature, compared to northern popul
The Paleocene or Palaeocene, the "old recent", is a geological epoch that lasted from about 66 to 56 million years ago. It is the first epoch of the Paleogene Period in the modern Cenozoic Era; as with many geologic periods, the strata that define the epoch's beginning and end are well identified, but the exact ages remain uncertain. The Paleocene Epoch is bracketed by two major events in Earth's history, it started with the mass extinction event at the end of the Cretaceous, known as the Cretaceous–Paleogene boundary. This was a time marked by the demise of non-avian dinosaurs, giant marine reptiles and much other fauna and flora; the die-off of the dinosaurs left unfilled ecological niches worldwide. The Paleocene ended with the Paleocene–Eocene Thermal Maximum, a geologically brief interval characterized by extreme changes in climate and carbon cycling; the name "Paleocene" comes from Ancient Greek and refers to the "old" "new" fauna that arose during the epoch. The K–Pg boundary that marks the separation between Cretaceous and Paleocene is visible in the geological record of much of the Earth by a discontinuity in the fossil fauna and high iridium levels.
There is fossil evidence of abrupt changes in flora and fauna. There is some evidence that a substantial but short-lived climatic change may have happened in the early decades of the Paleocene. There are several theories about the cause of the K–Pg extinction event, with most evidence supporting the impact of a 10 km diameter asteroid forming the buried Chicxulub crater on the coast of Yucatan, Mexico; the end of the Paleocene was marked by a time of major change, one of the most significant periods of global change during the Cenozoic. The Paleocene–Eocene Thermal Maximum upset oceanic and atmospheric circulation and led to the extinction of numerous deep-sea benthic foraminifera and a major turnover in mammals on land; the Paleocene is divided into three stages, the Danian, the Selandian and the Thanetian, as shown in the table above. Additionally, the Paleocene is divided into six Mammal Paleogene zones; the early Paleocene was cooler and drier than the preceding Cretaceous, though temperatures rose during the Paleocene–Eocene Thermal Maximum.
The climate became warm and humid worldwide towards the Eocene boundary, with subtropical vegetation growing in Greenland and Patagonia, crocodilians swimming off the coast of Greenland, early primates evolving in the tropical palm forests of northern Wyoming. The Earth's poles were temperate. In many ways, the Paleocene continued processes. During the Paleocene, the continents continued to drift toward their present positions. Supercontinent Laurasia had not yet separated into three continents - Europe and Greenland were still connected, North America and Asia were still intermittently joined by a land bridge, while Greenland and North America were beginning to separate; the Laramide orogeny of the late Cretaceous continued to uplift the Rocky Mountains in the American west, which ended in the succeeding epoch. South and North America remained separated by equatorial seas. Africa was heading north towards Europe closing the Tethys Ocean, India began its migration to Asia that would lead to a tectonic collision and the formation of the Himalayas.
The inland seas in North America and Europe had receded by the beginning of the Paleocene, making way for new land-based flora and fauna. Warm seas circulated including the poles; the earliest Paleocene featured a low diversity and abundance of marine life, but this trend reversed in the epoch. Tropical conditions gave rise including coral reefs. With the demise of marine reptiles at the end of the Cretaceous, sharks became the top predators. At the end of the Cretaceous, the ammonites and many species of foraminifera became extinct. Marine fauna came to resemble modern fauna, with only the marine mammals and the Carcharhinid sharks missing. Terrestrial Paleocene strata overlying the K–Pg boundary is in places marked by a "fern spike": a bed rich in fern fossils. Ferns are the first species to colonize areas damaged by forest fires. In general, the Paleocene is marked by the development of modern plant species. Cacti and palm trees appeared. Paleocene and plant fossils are attributed to modern genera or to related taxa.
The warm temperatures worldwide gave rise to thick tropical, sub-tropical and deciduous forest cover around the globe with ice-free polar regions covered with coniferous and deciduous trees. With no large browsing dinosaurs to thin them, Paleocene forests were denser than those of the Cretaceous. Flowering plants, first seen in the Cretaceous, continued to develop and proliferate, along with them coevolved the insects that fed on these plants and pollinated them. Mammals had first appeared in the Late Triassic, evolving from advanced cynodonts, developed alongside the dinosaurs, exploiting ecological niches untouched by the larger and more famous Mesozoic animals: in the insect-rich fo
Mangoes are juicy stone fruit from numerous species of tropical trees belonging to the flowering plant genus Mangifera, cultivated for their edible fruit. The majority of these species are found in nature as wild mangoes; the genus belongs to the cashew family Anacardiaceae. Mangoes are native to South Asia, from where the "common mango" or "Indian mango", Mangifera indica, has been distributed worldwide to become one of the most cultivated fruits in the tropics. Other Mangifera species are grown on a more localized basis, it is the national fruit of India and Pakistan, the national tree of Bangladesh. It is the unofficial national fruit of the Philippines; the English word "mango" originated from the Malayalam word māṅṅa via Dravidian mankay and Portuguese manga during the spice trade period with South India in the 15th and 16th centuries. Mango is mentioned by Hendrik van Rheede, the Dutch commander of the Malabar region in his 1678 book, Hortus Malabaricus, about plants having economic value.
When mangoes were first imported to the American colonies in the 17th century, they had to be pickled because of lack of refrigeration. Other fruits were pickled and came to be called "mangoes" bell peppers, in the 18th century, the word "mango" became a verb meaning "to pickle". Mango trees grow to 35–40 m tall, with a crown radius of 10 m; the trees are long-lived. In deep soil, the taproot descends to a depth of 6 m, with profuse, wide-spreading feeder roots and anchor roots penetrating into the soil; the leaves are evergreen, simple, 15–35 cm long, 6–16 cm broad. The flowers are produced in terminal panicles 10–40 cm long. Over 500 varieties of mangoes are known, many of which ripen in summer, while some give a double crop; the fruit takes four to five months from flowering to ripen. The ripe fruit varies in size, color and eating quality. Cultivars are variously yellow, red, or green, carry a single flat, oblong pit that can be fibrous or hairy on the surface, which does not separate from the pulp.
The fruits may be somewhat round, oval, or kidney-shaped, ranging from 5–25 centimetres in length and from 140 grams to 2 kilograms in weight per individual fruit. The skin is leather-like, waxy and fragrant, with color ranging from green to yellow, yellow-orange, yellow-red, or blushed with various shades of red, pink or yellow when ripe. Ripe intact mangoes give off a distinctive resinous, sweet smell. Inside the pit 1–2 mm thick is a thin lining covering a single seed, 4–7 cm long. Mangoes have recalcitrant seeds which do not survive drying. Mango trees grow from seeds, with germination success highest when seeds are obtained from mature fruits. Mangoes have been cultivated in South Asia for thousands of years and reached Southeast Asia between the fifth and fourth centuries BCE. By the 10th century CE, cultivation had begun in East Africa; the 14th-century Moroccan traveler Ibn Battuta reported it at Mogadishu. Cultivation came to Brazil, the West Indies, Mexico, where an appropriate climate allows its growth.
The mango is now cultivated in warmer subtropical climates. Mangoes are grown in Andalusia, Spain, as its coastal subtropical climate is one of the few places in mainland Europe that permits the growth of tropical plants and fruit trees; the Canary Islands are another notable Spanish producer of the fruit. Other cultivators include North America and Central America, the Caribbean, Hawai'i, south and central Africa, China, South Korea, Pakistan and Southeast Asia. Though India is the largest producer of mangoes, it accounts for less than 1% of the international mango trade. Many commercial cultivars are grafted on to the cold-hardy rootstock of Gomera-1 mango cultivar from Cuba, its root system is well adapted to a coastal Mediterranean climate. Many of the 1,000+ mango cultivars are cultivated using grafted saplings, ranging from the "turpentine mango" to the Bullock's Heart. Dwarf or semidwarf varieties can be grown in containers. A wide variety of diseases can afflict mangoes. There are many hundreds of named mango cultivars.
In mango orchards, several cultivars are grown in order to improve pollination. Many desired cultivars are monoembryonic and must be propagated by grafting or they do not breed true. A common monoembryonic cultivar is'Alphonso', an important export product, considered as "the king of mangoes". Cultivars that excel in one climate may fail elsewhere. For example, Indian cultivars such as'Julie', a prolific cultivar in Jamaica, require annual fungicide treatments to escape the lethal fungal disease anthracnose in Florida. Asian mangoes are resistant to anthracnose; the current world market is dominated by the cultivar'Tommy Atkins', a seedling of'Haden' that first fruited in 1940 in southern Florida and was rejected commercially by Florida researchers. Growers and importers worldwide have embraced the cultivar for its exc
The Eocene Epoch, lasting from 56 to 33.9 million years ago, is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Paleocene Epoch to the beginning of the Oligocene Epoch; the start of the Eocene is marked by a brief period in which the concentration of the carbon isotope 13C in the atmosphere was exceptionally low in comparison with the more common isotope 12C. The end is set at a major extinction event called the Grande Coupure or the Eocene–Oligocene extinction event, which may be related to the impact of one or more large bolides in Siberia and in what is now Chesapeake Bay; as with other geologic periods, the strata that define the start and end of the epoch are well identified, though their exact dates are uncertain. The name Eocene comes from the Ancient Greek ἠώς and καινός and refers to the "dawn" of modern fauna that appeared during the epoch; the Eocene epoch is conventionally divided into early and late subdivisions.
The corresponding rocks are referred to as lower and upper Eocene. The Ypresian stage constitutes the lower, the Priabonian stage the upper; the Eocene Epoch contained a wide variety of different climate conditions that includes the warmest climate in the Cenozoic Era and ends in an icehouse climate. The evolution of the Eocene climate began with warming after the end of the Palaeocene–Eocene Thermal Maximum at 56 million years ago to a maximum during the Eocene Optimum at around 49 million years ago. During this period of time, little to no ice was present on Earth with a smaller difference in temperature from the equator to the poles. Following the maximum was a descent into an icehouse climate from the Eocene Optimum to the Eocene-Oligocene transition at 34 million years ago. During this decrease ice began to reappear at the poles, the Eocene-Oligocene transition is the period of time where the Antarctic ice sheet began to expand. Greenhouse gases, in particular carbon dioxide and methane, played a significant role during the Eocene in controlling the surface temperature.
The end of the PETM was met with a large sequestration of carbon dioxide in the form of methane clathrate and crude oil at the bottom of the Arctic Ocean, that reduced the atmospheric carbon dioxide. This event was similar in magnitude to the massive release of greenhouse gasses at the beginning of the PETM, it is hypothesized that the sequestration was due to organic carbon burial and weathering of silicates. For the early Eocene there is much discussion; this is due to numerous proxies representing different atmospheric carbon dioxide content. For example, diverse geochemical and paleontological proxies indicate that at the maximum of global warmth the atmospheric carbon dioxide values were at 700–900 ppm while other proxies such as pedogenic carbonate and marine boron isotopes indicate large changes of carbon dioxide of over 2,000 ppm over periods of time of less than 1 million years. Sources for this large influx of carbon dioxide could be attributed to volcanic out-gassing due to North Atlantic rifting or oxidation of methane stored in large reservoirs deposited from the PETM event in the sea floor or wetland environments.
For contrast, today the carbon dioxide levels are at 400 ppm or 0.04%. At about the beginning of the Eocene Epoch the amount of oxygen in the earth's atmosphere more or less doubled. During the early Eocene, methane was another greenhouse gas that had a drastic effect on the climate. In comparison to carbon dioxide, methane has much greater effect on temperature as methane is around 34 times more effective per molecule than carbon dioxide on a 100-year scale. Most of the methane released to the atmosphere during this period of time would have been from wetlands and forests; the atmospheric methane concentration today is 0.000179% or 1.79 ppmv. Due to the warmer climate and sea level rise associated with the early Eocene, more wetlands, more forests, more coal deposits would be available for methane release. Comparing the early Eocene production of methane to current levels of atmospheric methane, the early Eocene would be able to produce triple the amount of current methane production; the warm temperatures during the early Eocene could have increased methane production rates, methane, released into the atmosphere would in turn warm the troposphere, cool the stratosphere, produce water vapor and carbon dioxide through oxidation.
Biogenic production of methane produces carbon dioxide and water vapor along with the methane, as well as yielding infrared radiation. The breakdown of methane in an oxygen atmosphere produces carbon monoxide, water vapor and infrared radiation; the carbon monoxide is not stable so it becomes carbon dioxide and in doing so releases yet more infrared radiation. Water vapor traps more infrared than does carbon dioxide; the middle to late Eocene marks not only the switch from warming to cooling, but the change in carbon dioxide from increasing to decreasing. At the end of the Eocene Optimum, carbon dioxide began decreasing due to increased siliceous plankton productivity and marine carbon burial. At the beginning of the middle Eocene an event that may have triggered or helped with the draw down of carbon dioxide was the Azolla event at around 49 million years ago. With the equable climate during the early Eocene, warm temperatures in the arctic allowed for the growth of azolla, a floating aquatic fern, on the Arctic Ocean.
Compared to current carb
Southeast Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China and Japan, east of India, west of Papua New Guinea, north of Australia. Southeast Asia is bordered to the north by East Asia, to the west by South Asia and the Bay of Bengal, to the east by Oceania and the Pacific Ocean, to the south by Australia and the Indian Ocean; the region is the only part of Asia that lies within the Southern Hemisphere, although the majority of it is in the Northern Hemisphere. In contemporary definition, Southeast Asia consists of two geographic regions: Mainland Southeast Asia known as Indochina, comprising parts of Northeast India, Laos, Thailand and West Malaysia. Maritime Southeast Asia known as Nusantara, the East Indies and Malay Archipelago, comprises the Andaman and Nicobar Islands of India, East Malaysia, the Philippines, East Timor, Christmas Island, the Cocos Islands. Taiwan is included in this grouping by many anthropologists; the region lies near the intersection of geological plates, with both heavy seismic and volcanic activities.
The Sunda Plate is the main plate of the region, featuring all Southeast Asian countries except Myanmar, northern Thailand, northern Laos, northern Vietnam, northern Luzon of the Philippines. The mountain ranges in Myanmar and peninsular Malaysia are part of the Alpide belt, while the islands of the Philippines are part of the Pacific Ring of Fire. Both seismic belts meet in Indonesia, causing the region to have high occurrences of earthquakes and volcanic eruptions. Southeast Asia covers about 4.5 million km2, 10.5% of Asia or 3% of earth's total land area. Its total population is about 8.5 % of the world's population. It is the third most populous geographical region in the world after East Asia; the region is culturally and ethnically diverse, with hundreds of languages spoken by different ethnic groups. Ten countries in the region are members of ASEAN, a regional organization established for economic, military and cultural integration amongst its members; the region, together with part of South Asia, was well known by Europeans as the East Indies or the Indies until the 20th century.
Chinese sources referred the region as 南洋, which means the "Southern Ocean." The mainland section of Southeast Asia was referred to as Indochina by European geographers due to its location between China and the Indian subcontinent and its having cultural influences from both neighboring regions. In the 20th century, the term became more restricted to territories of the former French Indochina; the maritime section of Southeast Asia is known as the Malay Archipelago, a term derived from the European concept of a Malay race. Another term for Maritime Southeast Asia is Insulindia, used to describe the region between Indochina and Australasia; the term "Southeast Asia" was first used in 1839 by American pastor Howard Malcolm in his book Travels in South-Eastern Asia. Malcolm only included the Mainland section and excluded the Maritime section in his definition of Southeast Asia; the term was used in the midst of World War II by the Allies, through the formation of South East Asia Command in 1943.
SEAC popularised the use of the term "Southeast Asia," although what constituted Southeast Asia was not fixed. However, by the late 1970s, a standard usage of the term "Southeast Asia" and the territories it encompasses had emerged. Although from a cultural or linguistic perspective the definitions of "Southeast Asia" may vary, the most common definitions nowadays include the area represented by the countries listed below. Ten of the eleven states of Southeast Asia are members of the Association of Southeast Asian Nations, while East Timor is an observer state. Papua New Guinea has stated that it might join ASEAN, is an observer. Sovereignty issues exist over some territories in the South China Sea; some southern parts of Mainland China, as well as Hong Kong and Taiwan, are considered as part of Southeast Asia by some authors. * Administrative centre in Putrajaya. Southeast Asia is geographically divided into two subregions, namely Mainland Southeast Asia and Maritime Southeast Asia. Mainland Southeast Asia includes: Maritime Southeast Asia includes: The Andaman and Nicobar Islands of India are geographically considered part of Maritime Southeast Asia.
Eastern Bangladesh and Northeast India have strong cultural ties with Southeast Asia and sometimes considered both South Asian and Southeast Asian. Sri Lanka has on some occasions been considered a part of Southeast Asia because of its cultural ties to mainland Southeast Asia; the rest of the island of New Guinea, not part of Indonesia, Papua New Guinea, is sometimes included, so are Palau and the Northern Mariana Islands, which were all part of the Spanish East Indies with strong cultural and linguistic ties to the region the Philippines. The eastern half of Indonesia and East Timor are considered to be biogeographically part of Oceania due to its distinctive faunal features. New Guinea and its surrounding islands are geologically considered as a part of Australian continent, connected via the Sahul Shelf; the region
André Joseph Guillaume Henri Kostermans
Dr. André Joseph Guillaume Henri'Dok' Kostermans was an Indonesian botanist of Dutch ancestry, he was born in Purworejo, Dutch East Indies, educated at Utrecht University, taking his doctoral degree in 1936 with a paper on Surinamese Lauraceae. He spent most of his professional life studying the plants of southeastern Asia, settled at Buitenzorg Bogor, Indonesia. At an early stage in his career he contributed a number of family treatments to Pulle's Flora of Suriname. Kostermans was interested in Lauraceae and Dipterocarpaceae. In years he turned his attention to Asian Anacardiaceae, he was a productive worker and published extensively on other groups. The genus Kostermansia Soegeng, of the family Bombacaceae, over 50 species were named in his honour. Kostermans suffered a heart attack in March 1991, but his letter to his friend written in April 1991 stated "some writing putting the finishing touch to a fat manuscript on the Mango species... If I am lucky I shall have a chance to see it." Kostermans did live to see it published by Academic Press in 1993.
He died in Indonesia in 1994. ASPT NEWSLETTER 9 January 1995 URL accessed 26 March 2006. Nationaal Herbarium Nederland: André Joseph Guillaume Henri Kostermans Image of grave
India known as the Republic of India, is a country in South Asia. It is the seventh largest country by area and with more than 1.3 billion people, it is the second most populous country as well as the most populous democracy in the world. Bounded by the Indian Ocean on the south, the Arabian Sea on the southwest, the Bay of Bengal on the southeast, it shares land borders with Pakistan to the west. In the Indian Ocean, India is in the vicinity of Sri Lanka and the Maldives, while its Andaman and Nicobar Islands share a maritime border with Thailand and Indonesia; the Indian subcontinent was home to the urban Indus Valley Civilisation of the 3rd millennium BCE. In the following millennium, the oldest scriptures associated with Hinduism began to be composed. Social stratification, based on caste, emerged in the first millennium BCE, Buddhism and Jainism arose. Early political consolidations took place under the Gupta empires. In the medieval era, Zoroastrianism and Islam arrived, Sikhism emerged, all adding to the region's diverse culture.
Much of the north fell to the Delhi Sultanate. The economy expanded in the 17th century in the Mughal Empire. In the mid-18th century, the subcontinent came under British East India Company rule, in the mid-19th under British Crown rule. A nationalist movement emerged in the late 19th century, which under Mahatma Gandhi, was noted for nonviolent resistance and led to India's independence in 1947. In 2017, the Indian economy was the world's sixth largest by nominal GDP and third largest by purchasing power parity. Following market-based economic reforms in 1991, India became one of the fastest-growing major economies and is considered a newly industrialised country. However, it continues to face the challenges of poverty, corruption and inadequate public healthcare. A nuclear weapons state and regional power, it has the second largest standing army in the world and ranks fifth in military expenditure among nations. India is a federal republic governed under a parliamentary system and consists of 29 states and 7 union territories.
A pluralistic and multi-ethnic society, it is home to a diversity of wildlife in a variety of protected habitats. The name India is derived from Indus, which originates from the Old Persian word Hindush, equivalent to the Sanskrit word Sindhu, the historical local appellation for the Indus River; the ancient Greeks referred to the Indians as Indoi, which translates as "The people of the Indus". The geographical term Bharat, recognised by the Constitution of India as an official name for the country, is used by many Indian languages in its variations, it is a modernisation of the historical name Bharatavarsha, which traditionally referred to the Indian subcontinent and gained increasing currency from the mid-19th century as a native name for India. Hindustan is a Middle Persian name for India, it was introduced into India by the Mughals and used since then. Its meaning varied, referring to a region that encompassed northern India and Pakistan or India in its entirety; the name may refer to either the northern part of India or the entire country.
The earliest known human remains in South Asia date to about 30,000 years ago. Nearly contemporaneous human rock art sites have been found in many parts of the Indian subcontinent, including at the Bhimbetka rock shelters in Madhya Pradesh. After 6500 BCE, evidence for domestication of food crops and animals, construction of permanent structures, storage of agricultural surplus, appeared in Mehrgarh and other sites in what is now Balochistan; these developed into the Indus Valley Civilisation, the first urban culture in South Asia, which flourished during 2500–1900 BCE in what is now Pakistan and western India. Centred around cities such as Mohenjo-daro, Harappa and Kalibangan, relying on varied forms of subsistence, the civilization engaged robustly in crafts production and wide-ranging trade. During the period 2000–500 BCE, many regions of the subcontinent transitioned from the Chalcolithic cultures to the Iron Age ones; the Vedas, the oldest scriptures associated with Hinduism, were composed during this period, historians have analysed these to posit a Vedic culture in the Punjab region and the upper Gangetic Plain.
Most historians consider this period to have encompassed several waves of Indo-Aryan migration into the subcontinent from the north-west. The caste system, which created a hierarchy of priests and free peasants, but which excluded indigenous peoples by labeling their occupations impure, arose during this period. On the Deccan Plateau, archaeological evidence from this period suggests the existence of a chiefdom stage of political organisation. In South India, a progression to sedentary life is indicated by the large number of megalithic monuments dating from this period, as well as by nearby traces of agriculture, irrigation tanks, craft traditions. In the late Vedic period, around the 6th century BCE, the small states and chiefdoms of the Ganges Plain and the north-western regions had consolidated into 16 major oligarchies and monarchies that were known as the mahajanapadas; the emerging urbanisation gave rise to non-Vedic religious movements, two of which became independent religions. Jainism came into prominence during the life of Mahavira.
Buddhism, based on the teachings of Gautama Buddha, attracted followers from all social classes excepting the middle