Main topographic areas and their locations in South Asia, Central Asia and West Asia

Refers to South Asia, between Southeast Asia and Southwest Asia. The latitude is 0-40 N (north latitude) and the longitude is 60 E (east longitude)-100 E. The land is basically in the area of10 N-30 N, roughly between the Himalayas and the Indian Ocean. There are seven countries in South Asia, among which Nepal and Bhutan are landlocked countries, India, Pakistan and Bangladesh are coastal countries, and Sri Lanka and Maldives are island countries. Pakistan, India, Nepal, Bhutan and Kashmir are adjacent to China. The topography of South Asia is divided into three parts: the Himalayas in the north; In the middle is the Indus-Ganges Plain; Deccan Plateau is in the south, and East and West Kochi Mountains are on the east and west sides of the plateau. The distance from north to south and from east to west is about 3100km, covering an area of about 4.37 million square kilometers. With a population of over 654.38 billion, it speaks more than 200 languages. In the north, there are tall Himalayas separated from the main body of the Asian continent, and the Bay of Bengal, the Arabian Sea and the Indian Ocean surround the east, west, north and south, which are geographically independent from each other, so it is also called the South Asian subcontinent (or subcontinent for short). Most areas have a tropical monsoon climate, and a year is divided into hot season (March-May), rainy season (June-September) and dry season (10 to February of the following year). The northern Himalayas has a alpine climate. There is a certain tropical desert climate distribution in the Indus Valley. The seasonal movement of pressure belt and wind belt makes southwest monsoon blow in summer and northeast monsoon blow in winter, which is one of the main reasons for the formation of tropical monsoon climate. The average elevation of Himalayas between northern Asia and inland Asia is over 6000m, with 14 peaks over 8000m. Mount Everest between Nepal, India and China is 8844.43m above sea level, which is the highest peak in the world. The vertical changes of climate, soil and vegetation are remarkable. In the middle, the Indus River, Ganges River and Brahmaputra River are alluvial plains with dense river networks, numerous irrigation canals and developed agriculture. In the south are Deccan Plateau and coastal plain on the east and west sides. Between the plateau and the coastal plain are the East Kochi Mountains and the West Kochi Mountains. Rivers such as Godavari and Krishna flow into the Bay of Bengal from west to east. Rich in rice, wheat, sugarcane, jute, rapeseed, cotton, tea and so on. Rich in coal, iron, manganese, mica, gold and other minerals.

The continental part from the south of the Himalayas to the Indian Ocean is called the "South Asian subcontinent". Because the Himalayas separate South Asia from other parts of Asia, South Asia has formed a relatively independent unit in geography. And "South Asia" is composed of most of the South Asian subcontinent and the nearby islands in the Indian Ocean. The northern part is a narrow and rugged mountain on the south side of the Himalayas, the middle part is a slightly curved and wide Ganges-Indus lowland, and the southern part is high in the west and low in the east, with gentle ups and downs.

The boundaries in South Asia are obvious. Young folded mountains (such as Suleiman Mountains in the northwest, Karakorum Mountains in the north, Himalayas, Badakai Mountains and Arakan Mountains in the east, etc.). ) It faces the peninsula in the north and the sea in the south. The central plain is alluvial by the Indus River and Ganges River. Originating in Tibet, China, the Indus River flows through the arid areas in western South Asia and flows into the Arabian Sea. The Ganges River originates in the Himalayan region in the northwest, flows through India and Bangladesh, flows into the Bay of Bengal, and the estuary is the Ganges Delta.

There is a very obvious relationship between geological structure and topography. Deccan Plateau in the south occupies most of the Indian Peninsula, which is a huge Precambrian ancient land mass, the core of the subcontinent and a part of Gondwana ancient land. At the end of Cretaceous, a large-scale basalt overflow occurred in the northwest of Deccan Plateau, covering an area of 400,000 square kilometers, forming the largest lava platform in the world. The topography of Deccan Plateau is a huge and ancient block, which slowly erodes to the northeast. The western part of the plateau is formed by the high mountains in the west, with a height of about 1, 000 ~ 1, 500 meters, and its western slope is a cliff. The eastern high mountain constitutes the eastern edge of the plateau, with a height of about 500 ~ 600 meters, low hilly landform and a vast coastal plain along the coast; There are many horsts and trenches in Deccan Plateau, which is an ancient, eroded, inclined, quasi-plain mound block cut by many rivers. The island of Sri Lanka was originally integrated with India in geological structure, but it was separated from India after settling in Park Strait and Manar Bay. The northern part is a part of the southern Himalayas, which is the product of Himalayan movement. The Himalayan mountains can be divided into three zones in structure: the northern zone, also known as the Tibet zone or the Tibetan Himalayan zone, is composed of rock layers from early Paleozoic to Tertiary; The central belt, also known as Xuefeng Himalayan belt or Himalayan belt, is mainly exposed by granite and gneiss, and there are many modern glaciers and Xuefeng; The southern belt, also known as the outer belt or the foothills Himalayan belt, is located between the Great Plains of India and the Himalayas, mainly in the lower foothills. The stratum is mainly tertiary sedimentary rocks, with a height of about 1 000m. India's great plains belong to the foreland of New Fall Mountain. Its predecessor is the Bay of Bengal and a part of the Arabian Sea. It is about 3000 kilometers long from east to west and 250-300 kilometers wide from north to south. It is one of the world-famous great plains.

Central Asia:

The five Central Asian countries refer to Kazakhstan, Uzbekistan, Kyrgyzstan, Turkmenistan and Tajikistan. It borders Xinjiang Uygur Autonomous Region in the east, Iran and Afghanistan in the south, Russian Federation in the north and Russian Federation and Azerbaijan in the west across the Caspian Sea. The five countries have a total area of nearly 4 million square kilometers and a total population of about 54 million 1995.

Generally speaking, it is high in the southeast and low in the northwest. In Pamir region of Tajikistan and Tianshan region of western Kyrgyzstan, the mountains are high and steep, with an altitude of 4,000-5,000 meters, among which the production peak at an altitude of 7,495 meters and lenin peak at 7 134 meters are the most famous peaks in the world. The lowest point of land elevation132m in the former Soviet Union was found in Karadzi depression near Caspian Sea in western Kazakhstan. In the eastern and western regions, deserts and oases are between 200 and 400 meters above sea level, hills and grasslands are between 300 and 500 meters above sea level, and the eastern mountainous areas are about 1000 meters above sea level. There are more than 4,000 glaciers in Central Asia, with a total area of 1 1 1,000 square kilometers. The largest Philippine Decenco Glacier is 7 1 km long, including 33 tributaries, covering an area of 900 square kilometers. At the foot of the mountain is an endless dry and hot desert, and the horizontal line of the desert gradually unfolds in the dusty loess. Valley basins surrounded by mountains and oases scattered in the vast desert are the most vital places in Central Asia, which nourish the farmers here, while the vast northern grasslands and hillside grasslands gallop the ethnic groups on horseback.

Located in the hinterland of Eurasia, especially in the southeast, mountains block the warm and humid air currents in the Indian Ocean and the Pacific Ocean. The climate in this area is a typical continental climate, and its outstanding characteristics are as follows: First, the rain is scarce and extremely dry. Generally, the annual precipitation is below 300mm. The annual precipitation in the desert near Aral Sea and Turkmenistan is only 75- 100mm, while the annual precipitation in mountainous areas is 1000mm, and the south slope of Fergana Mountain can even reach 2000mm. However, the rainfall in some mountainous areas is less than that in desert areas. For example, the annual precipitation in Pamir is only 60mm. Central Asia can get10-130,000 calories per square centimeter of ground every year due to solar radiation, while Turkmenistan almost gets160,000 calories. According to scientific tests, the amount of sunshine obtained in summer at 40 degrees north latitude in Central Asia is not inferior to that in tropical areas. Extremely dry air and high temperature cause a lot of evaporation. The annual evaporation of the water surface in the Amu Darya Delta reaches 1.798 mm, which is 2 1 times larger than the precipitation here. Third, the temperature changes dramatically. In many places, the difference between the highest temperature during the day and the lowest temperature at night can reach 20-30℃. In Pamirs, there is a temperature difference of 40℃ every day. From the northernmost part of Kazakhstan to the southernmost part of Turkmenistan, the longitudinal span is 57 degrees to 35 degrees north latitude, which shows the transition from temperate zone to subtropical zone. In midsummer July, except in mountainous areas, the average temperature is generally between 26℃ and 32℃, while in winter January, the average temperature ranges from -20℃ in the northern end to 2℃ in the southern end.

The topography, landform, economic development and other factors in this area determine its population distribution and composition. The outstanding features are as follows: First, the population density is very small, with an average of only 12 people per square kilometer. Among them, Kazakhstan and Turkmenistan have only 6. 1 and 7.2 people per square kilometer on average, and only Uzbekistan has a relatively dense population, reaching 5 1.4 people; Second, the population distribution is extremely uneven. There are only 1-2 people per square kilometer in mountainous areas, and there are almost no people in Karakum Desert, Kizilkum Desert and Central Kazakhstan Desert, while there are a large number of people around oases and big cities, such as the rich Fergana Valley with 300-400 people per square kilometer. The Chu River Basin, where Bishkek, the capital of Kyrgyzstan, is located, only accounts for112 of the territory of the Republic of China, but it concentrates 35% of the population of the Republic of China. Third, the birth rate and natural growth rate are high. The birth rate in Central Asian countries is generally above 30‰, and the natural growth rate is around 25‰. This situation is similar to that of the least developed countries in the world and is not suitable for their economic development; Fourth, the absolute population has increased rapidly since this century, especially in the last two or three decades. Take Kyrgyzstan as an example. In the 1990s, the population increased by 5.6 times, doubled in the last 30 years, and the absolute population increased by more than 2 million. The same is true of Uzbekistan, where the population was 5 million in 1959, doubled in 1979 and nearly doubled in1050,000. Fifth, urbanization has made great progress since this century. The urban population has increased from about 10% to about 40%, among which some areas in Kazakhstan have the highest level of urbanization, such as Karaganda, Jazkazgan and Mangosteen, and urban residents account for 80-90% of the total population. Before the 1970s, the growth of urban population mainly came from European immigrants, and after the 1970s, it was mainly * * * and internal population mobility. However, in some areas of Central Asia, such as Turkmenistan and Tajikistan, the proportion of urban population has declined in recent years because the natural growth rate of rural population greatly exceeds that of urban population and Russian immigrants.

The "Shanghai Five" was born on1April 26th, 996. Its original intention was to enhance military trust in the border areas of China, Russian Federation, Kazakhstan, Kyrgyzstan and Tajikistan and to jointly seek border peace. Therefore, as early as the early 1990s, China and the above four countries began negotiations on border disarmament and strengthening military mutual trust in border areas. On the basis of positive progress in the negotiations,1On April 26th, 1996, the heads of state of China, Russia, Kazakhstan, Kyrgyzstan and Tajikistan met for the first time in Shanghai and signed the Agreement on Strengthening Trust in the Military Field in Border Areas. 1On April 24, 1997, the heads of state of the five countries held their second meeting in Moscow and signed the Agreement on Mutual Reduction of Military Forces in Border Areas. The "Shanghai Five" is gradually developing into an open regional multilateral cooperation mechanism. 1998 The Almaty Joint Statement states: "The cooperation among the five countries is open and not directed against third countries. ..... proceeding from the reality of the region, all parties agreed to actively carry out bilateral and regional dialogues and consultations on security issues, and welcomed all countries in the region interested in this to participate in this process. " In July 2000, the five heads of state paid tribute to the presidents of Uzbekistan and Iraq. Huh? Karimov welcomed the Dushanbe Summit and said in the Dushanbe statement: "All parties support Uzbekistan's initiative to establish a nuclear-weapon-free zone in Central Asia and believe that the treaty on a nuclear-weapon-free zone in Central Asia should conform to the principles and standards of similar documents that have been implemented." In June 20001,the five heads of state will meet again in Shanghai, and Uzbekistan will also attend the meeting. This meeting will determine the development direction of the "Shanghai Five" in the 2 1 century, so it is of milestone significance in the development history of the "Shanghai Five".

West Asia:

The geographical region of southwest Asia. Located at the junction of Asia, Africa and Europe, between the Arabian Sea, the Red Sea, the Mediterranean Sea, the Black Sea and the Caspian Sea (inland lakes), it connects Europe, Asia and Africa, so it is called "the land of five seas and three continents". Including Iranian Plateau, Arabian Peninsula, Mesopotamia Plain and Asia Minor Peninsula. Including Iran, Iraq and Georgia in Asia, Armenia and Azerbaijan in Asia, Turkey in Asia, Syria, Jordan, Israel, Palestine, Egypt, Saudi Arabia, Bahrain, Qatar, Yemen and Oman in Asia. The area is about 7 1.8 million square kilometers (including 60,000 square kilometers of Egypt in Sinai Peninsula and excluding 20,000 square kilometers of Turkey in Europe), accounting for about 1.6% of the total area of Asia.

Plateau-dominated topography: the Iranian plateau in the east of West Asia, the Armenian volcanic plateau in the west and the Anatolian plateau in Asia Minor are all inland plateaus, surrounded by folded mountains formed during the Alpine-Himalayan movement, with many tall mountain systems distributed on the edge. The Arabian Peninsula in the southwest is a platform plateau formed by Precambrian ancient land. The plain area is not large, mainly including Mesopotamia plain and Kula valley plain in Transcaucasia. In geological history, there have been many volcanic activities in the West Asia Plateau, forming a large area of lava platform. There are many volcanoes, and influenced by neotectonic movement, modern volcanoes and earthquakes are also quite frequent. The external force landform is mainly drought and sandstorm landform, and the desert is widely distributed.

The Tropic of Cancer, which has a dry climate, runs through the central part of this area, and most areas are controlled by subtropical high and dry northeast trade winds. At the same time, the southwest of the region is adjacent to arid North Africa, and the plateau edge is surrounded by tall mountains, with a dry climate, mostly tropical and subtropical desert climate. Less precipitation and strong evaporation. Most of the annual precipitation is below 250 mm, and the areas with more precipitation generally do not exceed 500 mm. Only mountainous areas and Mediterranean coastal areas are rich in precipitation. The east coast of the Mediterranean belongs to the Mediterranean climate, with rainy winters and dry summers. Arabian Peninsula is a world-famous arid climate zone with little precipitation. Limited by precipitation and topography, the inland river basin and no-flow area in this area are vast, with poor surface runoff and sparse river network. Except the Euphrates and Tigris rivers, most of them are short rivers, most of which originate from the mountainous areas on the edge of the plateau and are replenished by glacial snowmelt water. The amount of river water is small, and the seasonal changes are significant.

More than 220 million residents (1990). It is one of the regions with the fastest population growth after the war. The average annual natural growth rate of population was 25.8‰ in 1950s, 27.5‰ in 1960s, 29.2‰ in 1970s and over 30‰ in 1980s. Far more than the average level of developing countries, but West Asia is still one of the most sparsely populated areas in the world, with an average population density of 22 people per square kilometer, and the population distribution is extremely uneven, especially in the Mediterranean coast and the two rivers and plains. The desert area is sparsely populated. There are a large number of foreign workers in West Asia, concentrated in several oil exporting countries in the Persian Gulf, accounting for about 80% of the total labor force, which has become a labor market with world significance. The urbanization of population is progressing rapidly, rising from 22% of 1950 to over 50%. Kuwait (93%) and other oil-producing countries are as high as 80 ~ 90%. Megacities with a population of one million have increased from 1 to 13, and Tehran (6 million people) has developed into a megacity. There is a great difference between urban and rural areas, and rural areas still live a backward nomadic life. Arabs account for more than 1/2, which is one of the main gathering areas of Arabs in the world. It is concentrated in south-central China: Arabian Peninsula, Mesopotamia Plain and Mediterranean countries. The peninsula in Asia Minor is mostly Turks, the Iranian plateau is mostly Persians, and Israel is mainly inhabited by Jews in the world (about 83%). Cyprus is mainly composed of Greeks and Turks, and Azerbaijanis, Georgians and Armenians live in Transcaucasia.

According to its economic characteristics, it can be divided into two economic types, namely, oil exporting countries and non-oil exporting countries. Oil exporting countries include Saudi Arabia, United Arab Emirates, Qatar, Bahrain, Kuwait, Iraq, Iran and Oman. Oil is the economic lifeline of all countries, and the proportion of oil industry in gross national product, national income and export value is absolutely dominant. Construction, transportation, processing and commerce are all based on oil production. After the war, the economy developed very rapidly, and the per capita gross national product ranked first in the world. A single economic structure is often influenced by the international market, especially the energy market. To this end, countries are adjusting their economic development strategies and gradually diversifying their development. Labor resources are insufficient, and a large number of foreign workers and technicians enter from abroad every year, becoming an important labor market in the world. State-owned enterprises are dominant, and various economic components coexist. The economies of non-oil exporting countries are mainly agriculture and animal husbandry. Mining and processing industries are relatively weak, giving full play to their geographical advantages, making considerable profits from oil in transportation, processing and providing services, and charging high transit fees to obtain considerable income. Of course, the level of development varies greatly among countries. West Asia has a long history of agricultural development. Affected by climate, irrigated agriculture plays an important role. The main food crops are wheat, barley and beans, followed by millet and rice. Cash crops such as cotton, tobacco and sugar beet. Animal products and dried and fresh fruits are important export products, such as jujube, hazelnut, pistachio, pomegranate, olive, purple lamb and Ankara goat. Cultivated land is concentrated in coastal areas, river valleys and oases, and grassland pastures in mountainous areas and plateaus are mainly animal husbandry. The self-sufficiency rate of agricultural products is low, and it has become one of the main import areas of agricultural and livestock products in the world.

Since ancient times, West Asia has been the main road of communication between the East and the West. The Silk Road starts from Xi, China, goes out of Xinjiang along the Hexi Corridor, passes through Pakistan, and then goes from West Asia to Europe. Now, in addition to the land and international routes connecting the three continents, the Suez Canal connecting the Mediterranean Sea and the Red Sea also connects the Atlantic Ocean and the Indian Ocean. The Northwest Strait is the only exit from the Black Sea to the Mediterranean Sea. The Persian Gulf in the south is the main waterway for world oil transportation, while the the Strait of Hormuz and Mande Strait are the "throats" of offshore oil transportation lines. Therefore, West Asia is strategically located in a modern land, sea and air transportation hub connecting three continents and connecting two oceans and five seas.