Asia is the Earth's largest and most populous continent, located primarily in the eastern andnorthern hemispheres. Though it covers only 8.7% of the Earth's total surface area, it comprises 30% of Earth's land area, and has historically been home to the bulk of the planet's human population (currently roughly 60%). Asia is notable for not only overall large size and population, but unusually dense and large settlements as well as vast barely populated regions within the continent of 4.4 billion people. Asia has exhibited economic dynamism (particularly East Asia) as well as robust population growth during the 20th century, but overall population growth has since fallen to world average levels.

The boundaries of Asia are traditionally determined as that of Eurasia which is not Europe, as there is no clear geographical separation between them, and Asia is in itself originally a European definition. The most commonly accepted boundaries place Asia to the east of the Suez Canal, the Ural River, and the Ural Mountains, and south of theCaucasus Mountains and the Caspian and Black Seas.^[4] It is bounded on the east by the Pacific Ocean, on the south by the Indian Ocean and on the north by the Arctic Ocean.

Given its size and diversity, the concept of Asia—a name dating back to classical antiquity—may actually have more to do with human geography than physical geography.^[5] Asia varies greatly across and within its regions with regard to ethnic groups, cultures, environments, economics, historical ties and government systems. It also has a mix of many different climates ranging from the equatorial south via the hot desert in the Middle East, temperate areas in the east and the extremely continental centre to vast subarctic and polar areas in Siberia.

The border between Asia and Europe has historically been determined by Europeans^[which?] only.^{[dubious – discuss]} The original distinction between the two was made by the ancient Greeks. They used the Aegean Sea, the Dardanelles, theSea of Marmara, the Bosporus, the Black Sea, the Kerch Strait, and the Sea of Azov as the border between Asia and Europe. The Nile was often used as the border between Asia and Africa (then called Libya), although some Greek geographers suggested the Red Sea would form a better boundary.^[6] Darius' canal between the Nile and the Red Sea introduced considerable variation in opinion. Under the Roman Empire, the Don River emptying into the Black Sea was the western border of Asia. It was the northernmost navigable point of the European shore.^{[citation needed]} In the 15th century the Red Sea became established as the boundary between Africa and Asia, replacing the Nile.^[6]

The current boundary between Asia and Africa is the Red Sea, the Gulf of Suez, and the Suez Canal. This makes Egypt a transcontinental country, with the Sinai peninsula in Asia and the remainder of the country in Africa.

The Don River became unsatisfactory to northern Europeans when Peter the Great, king of the Tsardom of Russia, defeating rival claims of Sweden and the Ottoman Empire to the eastern lands, and armed resistance by the tribes ofSiberia, synthesized a new Russian Empire extending to the Ural Mountains and beyond, founded in 1721. The major geographical theorist of the empire was actually a former Swedish prisoner-of-war, taken at the Battle of Poltava in 1709 and assigned to Tobolsk, where he associated with Peter's Siberian official, Vasily Tatishchev, and was allowed freedom to conduct geographical and anthropological studies in preparation for a future book.^{[citation needed]}

In Sweden, five years after Peter's death, in 1730 Philip Johan von Strahlenberg published a new atlas proposing the Urals as the border of Asia. The Russians were enthusiastic about the concept, which allowed them to keep their European identity in geography. Tatishchev announced that he had proposed the idea to von Strahlenberg. The latter had suggested the Emba Riveras the lower boundary. Over the next century various proposals were made until the Ural River prevailed in the mid-19th century. The border had been moved perforce from the Black Sea to the Caspian Sea into which the Ural River projects.^[7] In the maps of the period, Transcaucasia was counted as Asian. The incorporation of most of that region into the Soviet Union tended to push views of the border to the south. Asian cultures had no say in this system of determining the imaginary boundaries separating them from Europe.^{[citation needed]}

The border between Asia and the loosely defined region of Oceania is usually placed somewhere in the Malay Archipelago. The terms Southeast Asia and Oceania, devised in the 19th century, have had several vastly different geographic meanings since their inception. The chief factor in determining which islands of the Malay Archipelago are Asian has been the location of the colonial possessions of the various empires there (not all European). Lewis and Wigen assert, "The narrowing of 'Southeast Asia' to its present boundaries was thus a gradual process."^[6]

Geographical Asia is a cultural artifact of European conceptions of the world being imposed onto other cultures, an imprecise concept causing endemic contention about what it means. Asia is larger and more culturally diverse than Europe.^[8] It does not exactly correspond to the cultural borders of its various types of constituents.^[9]

From the time of Herodotus a minority of geographers have rejected the three-continent system (Europe, Africa, Asia) on the grounds that there is no or is no substantial physical separation between them.^[5] For example, Sir Barry Cunliffe, the emeritus professor of European archeology at Oxford, argues that Europe has been geographically and culturally merely "the western excrescence of the continent of Asia".^[10] Geographically, Asia is the major eastern constituent of the continent of Eurasia with Europe being a northwestern peninsula of the landmass – or of Afro-Eurasia; geologically, Asia, Europe and Africa make up a single continuous landmass (except for the Suez Canal) and share a common continental shelf. Almost all of Europe and the better part of Asia sit atop the Eurasian Plate, adjoined on the south by the Arabian and Indian Plate and with the easternmost part of Siberia (east of the Chersky Range) on the North American Plate.

The English word, "Asia," was originally a concept of Greek civilization.^[11] The place name, "Asia", in various forms in a large number of modern languages is of unknown ultimate provenience. Its etymology and language of origin are uncertain. It appears to be one of the most ancient of recorded names. A number of theories have been published. English Asia can be traced through the formation of English literature to Latin literature, where it has the same form, Asia. Whether all uses and all forms of the name derive also from the Latin of the Roman Empire is much less certain.

Latin Asia and Greek Ἀσία appear to be the same word. Roman authors translated Ἀσία as Asia. The Romans named a province Asia (Roman province), which roughly corresponds with modern-day central-western Turkey. There was an Asia Minor and an Asia Major located in modern-day Iraq. As the earliest evidence of the name is Greek, it is likely circumstantially that Asia came from Ἀσία, but ancient transitions, due to the lack of literary contexts, are difficult to catch in the act. The most likely vehicles were the ancient geographers and historians, such as Herodotus, who were all Greek. Ancient Greek certainly evidences early and rich uses of the name.^[12]

The first continental use of Asia is attributed to Herodotus (about 440 BC), not because he innovated it, but because his Histories are the earliest surviving prose to describe it in any detail. He defines it carefully,^[13] mentioning the previous geographers whom he had read, but whose works are now missing. By it he means Anatoliaand the Persian Empire, in contrast to Greece and Egypt. Herodotus comments that he is puzzled as to why three women's names were "given to a tract which is in reality one" (Europa, Asia, and Libya, referring to Africa), stating that most Greeks assumed that Asia was named after the wife of Prometheus (i.e. Hesione), but that theLydians say it was named after Asies, son of Cotys, who passed the name on to a tribe at Sardis.^[14] In Greek mythology, "Asia" (Ἀσία) or "Asie" (Ἀσίη) was the name of a "Nymph or Titan goddess of Lydia."^[15]

Herodotus' geographical puzzlement was perhaps only a form of disagreement, as, having read the earlier Greek poetry along with everyone else literate, he would have known perfectly well why places received female names. Athens, Mycenae, Thebes and many other locations in fact had them. In ancient Greek religion, places were under the care of female divinities, parallel to guardian angels. The poets detailed their doings and generations in allegoric language salted with entertaining stories, which subsequently playwrights transformed into classical Greek drama and became "Greek mythology."

For example, Hesiod mentions the daughters of Tethys and Ocean, among whom are a "holy company", "who with the Lord Apollo and the Rivers have youths in their keeping."^[16] Many of these are geographic: Doris, Rhodea, Europa, Asia. Hesiod explains:^[17]

The Iliad (attributed by the ancient Greeks to Homer) mentions two Phrygians (the tribe that replaced the Luvians in Lydia) in the Trojan War named Asios (an adjective meaning "Asian");^[18] and also a marsh or lowland containing a marsh in Lydia as ασιος.^[19]

Before Greek poetry, the Aegean Sea area was in a Greek Dark Age, at the beginning of which syllabic writing was lost and alphabetic writing had not begun. Prior to then in the Bronze Age the records of the Assyrian Empire, the Hittite Empire and the various Mycenaean states of Greece mention a region undoubtedly Asia, certainly in Anatolia, including if not identical to Lydia. These records are administrative and do not include poetry.

The Mycenaean states were destroyed about 1200 BC by unknown agents although one school of thought assigns the Dorian invasion to this time. The burning of the palaces baked clay diurnal administrative records written in a Greek syllabic script called Linear B, deciphered by a number of interested parties, most notably by a young World War II cryptographer, Michael Ventris, subsequently assisted by the scholar, John Chadwick. A major cache discovered by Carl Blegen at the site of ancientPylos included hundreds of male and female names formed by different methods.

Some of these are of women held in servitude (as study of the society implied by the content reveals). They were used in trades, such as cloth-making, and usually came with children. The epithet, lawiaiai, "captives," associated with some of them identifies their origin. Some are ethnic names. One in particular, aswiai, identifies "women of Asia."^[20] Perhaps they were captured in Asia, but some others, Milatiai, appear to have been of Miletus, a Greek colony, which would not have been raided for slaves by Greeks. Chadwick suggests that the names record the locations where these foreign women were purchased.^[21] The name is also in the singular, Aswia, which refers both to the name of a country and to a female of it. There is a masculine form, aswios. This Aswia appears to have been a remnant of a region known to the Hittites as Assuwa, centered on Lydia, or "Roman Asia." This name, Assuwa, has been suggested as the origin for the name of the continent "Asia".^[22] The Assuwa league was a confederation of states in western Anatolia, defeated by the Hittites under Tudhaliya I around 1400 BC.

Alternatively, the etymology of the term may be from the Akkadian word (w)aṣû(m), which means 'to go outside' or 'to ascend', referring to the direction of the sun at sunrise in the Middle East and also likely connected with the Phoenician word asa meaning east. This may be contrasted to a similar etymology proposed for Europe, as being from Akkadian erēbu(m) 'to enter' or 'set' (of the sun).

T.R. Reid supports this alternative etymology, noting that the ancient Greek name must have derived from asu, meaning 'east' in Assyrian (ereb for Europe meaning 'west').^[11] The ideas of Occidental (form Latin Occidens 'setting') and Oriental (from Latin Oriens for 'rising') are also European invention, synonymous with Western andEastern.^[11] Reid further emphasizes that it explains the Western point of view of placing all the peoples and cultures of Asia into a single classification, almost as if there were a need for setting the distinction between Western and Eastern civilizations on the Eurasian continent.^[11] Ogura Kazuo and Tenshin Okakura are two outspoken Japanese figures on the subject.^[11]

The history of Asia can be seen as the distinct histories of several peripheral coastal regions: East Asia, South Asia,Southeast Asia and the Middle East, linked by the interior mass of the Central Asian steppes.

The coastal periphery was home to some of the world's earliest known civilizations, each of them developing around fertile river valleys. The civilizations in Mesopotamia, the Indus Valley and the Huanghe shared many similarities. These civilizations may well have exchanged technologies and ideas such as mathematics and the wheel. Other innovations, such as writing, seem to have been developed individually in each area. Cities, states and empires developed in these lowlands.

The central steppe region had long been inhabited by horse-mounted nomads who could reach all areas of Asia from thesteppes. The earliest postulated expansion out of the steppe is that of the Indo-Europeans, who spread their languages into the Middle East, South Asia, and the borders of China, where the Tocharians resided. The northernmost part of Asia, including much of Siberia, was largely inaccessible to the steppe nomads, owing to the dense forests, climate and tundra. These areas remained very sparsely populated.

The center and the peripheries were mostly kept separated by mountains and deserts. The Caucasus and Himalayamountains and the Karakum and Gobi deserts formed barriers that the steppe horsemen could cross only with difficulty. While the urban city dwellers were more advanced technologically and socially, in many cases they could do little in a military aspect to defend against the mounted hordes of the steppe. However, the lowlands did not have enough open grasslands to support a large horsebound force; for this and other reasons, the nomads who conquered states in China, India, and the Middle East often found themselves adapting to the local, more affluent societies.

The Islamic Caliphate took over the Middle East and Central Asia during the Muslim conquests of the 7th century. TheMongol Empire conquered a large part of Asia in the 13th century, an area extending from China to Europe. Before the Mongol invasion, Song dynasty reportedly had approximately 120 million citizens; the 1300 census which followed the invasion reported roughly 60 million people.^[25]

The Black Death, one of the most devastating pandemics in human history, is thought to have originated in the arid plains of central Asia, where it then travelled along the Silk Road.^[26]

The Russian Empire began to expand into Asia from the 17th century, and would eventually take control of all of Siberia and most of Central Asia by the end of the 19th century. The Ottoman Empire controlled Anatolia, the Middle East, North Africa and the Balkans from the 16th century onwards. In the 17th century, the Manchuconquered China and established the Qing Dynasty. In the 16th century, the IslamicMughal Empire controlled much of India.

Asia is the largest continent on Earth. It covers 8.8% of the Earth's total surface area (or 30% of its land area), and has the largest coastline, at 62,800 kilometres (39,022 mi). Asia is generally defined as comprising the eastern four-fifths ofEurasia. It is located to the east of the Suez Canal and the Ural Mountains, and south of the Caucasus Mountains (or the Kuma–Manych Depression) and the Caspian and Black Seas.^[4][27] It is bounded on the east by the Pacific Ocean, on the south by theIndian Ocean and on the north by the Arctic Ocean. Asia is subdivided into 48 countries, two of them (Russia and Turkey) having part of their land in Europe.

Asia has extremely diverse climates and geographic features. Climates range from arctic and subarctic in Siberia to tropical in southern India and Southeast Asia. It is moist across southeast sections, and dry across much of the interior. Some of the largest daily temperature ranges on Earth occur in western sections of Asia. The monsoon circulation dominates across southern and eastern sections, due to the presence of the Himalayas forcing the formation of a thermal low which draws in moisture during the summer. Southwestern sections of the continent are hot. Siberia is one of the coldest places in the Northern Hemisphere, and can act as a source of arctic air masses for North America. The most active place on Earth for tropical cyclone activity lies northeast of the Philippines and south of Japan. The Gobi Desert is in Mongolia and the Arabian Desert stretches across much of the Middle East. The Yangtze River in China is the longest river in the continent. The Himalayas between Nepal and China is the tallest mountain range in the world. Tropical rainforests stretch across much of southern Asia and coniferous and deciduous forests lie farther north.

A survey carried out in 2010 by global risk analysis farm Maplecroft identified 16 countries that are extremely vulnerable to climate change. Each nation's vulnerability was calculated using 42 socio, economic and environmental indicators, which identified the likely climate change impacts during the next 30 years. The Asian countries ofBangladesh, India, Vietnam, Thailand, Pakistan and Sri Lanka were among the 16 countries facing extreme risk from climate change. Some shifts are already occurring. For example, in tropical parts of India with a semi-arid climate, the temperature increased by 0.4 °C between 1901 and 2003. A 2013 study by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) aimed to find science-based, pro-poor approaches and techniques that would enable Asia's agricultural systems to cope with climate change, while benefitting poor and vulnerable farmers. The study's recommendations ranged from improving the use of climate information in local planning and strengthening weather-based agro-advisory services, to stimulating diversification of rural household incomes and providing incentives to farmers to adopt natural resource conservation measures to enhance forest cover, replenish groundwater and use renewable energy.