[2020-02-25]我们如何解释世界上40%的人口生活在中国和印度这两个国家？相对于其他文明，这两种文明是如何聚集如此庞大的人口呢？

Balaji Viswanathan,Knowledge lover.
First, a quick clearing of a myth. Some people assume that India has had a runaway population disaster in the past century. The truth is that India's current share of world population is far less than historic levels and that India's population has been growing at less than the global average in the past two centuries. You can see the population of different countries over the human history.
Although India & China occupy "only" a tenth of Earth's land surface, their share of earth's hospitable land is close to a quarter. Vast chunks of earth are not really hospitable - Siberia, Antarctica, Greenland, Alaska, Sahara desert, most of Canada, Arabian desert and rain forests of Amazon and central Africa. The inland water resources of Mongolia, northern Mexico, central Australia, Central Asian Republics are too few. This rules out a sizeable chunk of earth's land for dense human settlement.
Let us now zoom to this critical zone around 30N (just north of Tropic of Cancer) where all major civilizations arose and almost all of modern religions came from. The people around this latitude shaped the world's history of ancient era.

Balaji Viswanathan，知识爱好者
首先，快速澄清一个荒诞的说法。一些人认为，在过去的一个世纪里，印度发生了一场人口失控的灾难。 事实是，印度目前在世界人口中所占的比例远远低于历史水平，而且在过去两个世纪里，印度人口的增长速度一直低于全球平均水平。 你可以看到人类历史上不同国家的人口。
尽管印度和中国“只”占据了地球陆地面积的十分之一，但它们在地球上适宜居住的土地所占的比例接近四分之一。 大片的地球其实并不适合人类居住——西伯利亚、南极洲、格陵兰岛、阿拉斯加、撒哈拉沙漠、加拿大大部分地区、阿拉伯沙漠、亚马逊热带雨林和非洲中部。 蒙古、墨西哥北部、澳大利亚中部和中亚各共和国的内陆水资源太少。 这就排除了地球上相当大一块土地成为人口稠密地区的可能性。
现在让我们放大到北纬30度左右的这个临界地带(北回归线北部) ，这里是所有主要文明的起源地，也是几乎所有现代宗教的起源地。 这个纬度附近的人们创造了世界古代的历史。

While Iran had civilizations going from the ancient era, it never had any major river to support a massive population growth. Israel was too small & had a constant outside intervention. Egypt outside the narrow Nile valley, most of Iraq (especially regions far from Tigris & Euphrates) and most parts of Arab peninsula were too dry & hot to support massive population settlement.
Northern India and Eastern China sit on massive alluvial plains created by rivers such as Indus+Ganga+Brahmaputra and Huang He+Yangtze rivers. The first recorded human civilizations grew on these river valley plains along with the plains created by Nile (Egypt) and Euphrates (modern Iraq). These river valleys provided the right conditions for the civilization, with water & silt for agriculture, tolerable climatic conditions and rivers for commerce.

虽然伊朗的文明从古代就开始了，但它一直没有一条主要的河流来支持大规模的人口增长。 以色列太小了，经常受到外界的干扰。 埃及在狭窄的尼罗河谷之外，伊拉克大部分地区(特别是离底格里斯和幼发拉底河很远的地区)和阿拉伯半岛的大部分地区都太干燥和炎热，无法支持大规模的人口定居。
印度北部和中国东部坐落在巨大的冲积平原上，这些冲积平原是由印度河 + 恒河 + 雅鲁藏布江和黄河 + 长江等河流形成的。 第一个有记载的人类文明是在这些河谷平原与尼罗河(埃及)和幼发拉底河(现代伊拉克)创造的平原上发展起来的。这些河谷为人类文明提供了适宜的条件，为农业提供了水和泥沙，为商业提供了可容忍的气候条件和河流。

There are only a handful of these big river valleys in the world, especially in this latitude. Overall there are about 26 major river basins (see map below) and only 16 of them are in the hospitable regions. India and China have 4 of the 16. Of the remaining 12, five of them are surrounded by massive rain forests. Three of them: Orange, Murray-Darling & Mississippi were a bit isolated to support a major civilization (although they all supported unique native cultures and are home to major cities now). That leaves the Nile, Danube, the Euphrates, Zambezi as the major cradles of civilizations outside India & China.
Besides the major ones, China has 50,000 rivers with 100 sq km or more in the catchment area. India has a lesser number of these rivers, but is well spread throughout the country. The rivers are neither too monstrous like the Amazon nor too small to feed the population.

世界上只有少数几个这样的大河谷，特别是在这个纬度。 总共有大约26条主要河流流域，其中只有16条位于适宜居住的地区。16条中，印度和中国占了4条。在剩下的12条中，有5条被巨大的热带雨林所包围。其中3条：奥兰治河，墨累-达令河和密西西比河，有点偏僻，不足以支持一个主要的文明(尽管他们都有独特的本土文化，并且现在是主要城市的所在地)。这使得尼罗河、多瑙河、幼发拉底河、赞比西河成为除印度和中国以外的主要文明发源地。
除主要河流外，中国还有5万条河流，流域面积达100平方公里以上。印度的这些河流数量较少，但是分布在全国各地。这些河流既不像亚马逊河那样可怕，也不会太小，足以养活人口。

In short India and China had multiple river systems that were both massive as well as hospitable that lead to huge food production. Instead of depending on a single river system (like Egypt), India and China each had more than 3 major river systems giving a sort of backup. Thus, when Indus valley civilization faltered, the civilization quickly picked up the slack near Ganges.
Food production:
In 2005, India and China together held 20% of world's arable land (land suitable for a major crop), producing 50% of world's rice and 30% of world's wheat, see land use statistics by country. This ratio would have been much higher two centuries ago when vast tracts of Brazil, Sibera, Australia and USA were not explored. While 50% of India is arable, less than 7% of Australia, Canada or Russia is arable even with the introduction of modern technology.

简而言之，印度和中国有多个河流系统，既庞大又适宜居住，以致粮食生产巨大。印度和中国没有像埃及那样依赖单一的河流系统，而是各自拥有三个以上的主要河流系统作为后盾。因此，当印度河流域文明发生动荡的时候，恒河附近的文明很快就恢复了生机。
食物生产：
2005年，印度和中国总共拥有世界上20% 的可耕地(适合主要作物的耕作土地) ，生产了世界上50% 的大米和30% 的小麦。 两个世纪前，当巴西、西伯利亚、澳大利亚和美国的大片土地还未被开发时，这个比例高得多。印度50% 的土地是可耕地，而即使采用了现代技术，澳大利亚、加拿大或俄罗斯也只有不到7% 的土地是可耕地。

The Mississippi river valley never had the benefit of other major civilizations close to it. Asian civilizations exhibited a lot of connectivity. The pottery technology of Indus, wheel of Sumer, writing system of Egypt and later the religion of Ganges (Buddhism) quickly spread to other civilizations enabling people to build ideas on top of best practices elsewhere.
When the Europeans came most of this population got decimated and thus US never had a population to rival Asia.
The arrival of Europeans solved this issue and the population of the US started exploding since 16th century growing 60 times since 1800. US is actually catching up. But, India and China have a huge headstart.
Both India and China were fortuitous to have been unified for sizable chunks of time since about 200 BC. Qin Dynasty unified China in about 206 BC and Ashoka unified India in about 250 BC.

密西西比河流域从来没有受益于其他主要文明的好处。亚洲文明表现出很多的联系性。印度河的陶器工艺、苏美尔的车轮、埃及的文字系统以及后来的恒河宗教(佛教)迅速传播到其他文明，使人们能够在其他地方进行最佳实践后建立思想。
当欧洲人来到美国时，这里的大部分原住民都遭到了灭绝，因此美国的人口数量根本无法与亚洲相提并论。
欧洲人的到来解决了这个问题，美国人口自16世纪以来开始爆炸式增长，自1800年以来增长了60倍。美国正在迎头赶上。 但是，印度和中国有着巨大的领先优势。
印度和中国都很幸运，自公元前200年左右以来，在很长的一段时间内实现了统一。公元前206年左右，秦朝统一了中国，公元前250年左右，阿育王统一了印度。

Paul Hsieh , 20+ year professional computer programmer.
Rice, and strong borders.seriously.  Rice is a ridiculously productive crop, probably at least as productive as wheat.  Both country's populations largely live off that. Also they have relatively stable borders -- so neither country has been taken over by a hostile force in any very serious way.  So in a sense, this leads to both countries having a kind of stasis.  People have lots of kids, because there's no reason not to.  Historically families restricting themselves to a smaller number of children in the hopes of paying more for an education for them was not much of a consideration until recently.By comparison, European countries have historically been at each other's throats under constant warfare.  Child mortality was just a way of life.  In modern times, Europeans and North Americans tend to follow family planning principles, knowing that more children are harder to take care of, and more expensive.

Paul Hsieh 20年以上的专业程序员
水稻，还有强壮的身体素质。说真的，水稻是一种荒唐的高产作物，可能至少和小麦一样高产。这两个国家的人口大部分都以此为生。 此外，它们的边界相对稳定，因此两国都没有被敌对势力用任何非常严重的方式接管。所以在某种意义上，这导致了两个国家都处于停滞状态。人们有很多孩子，因为没有理由不生。从历史上看，直到最近才开始考虑到：家庭为了孩子的教育费而生较少的孩子。相比之下，欧洲国家历来在不断地经历战争。儿童死亡率高是正常的。在现代，欧洲人和北美人倾向于遵循计划生育原则，因为他们知道更多的孩子更难照顾，花费也更高。

Jagannadh , lives in India
TL;DR: The population of any Country will depend on its demographic location with moderate, comfortable climatic conditions and water to survive.Let me explain in detail, If we'd  like to relocate to a place in new city or a new flat in some location, what would the basics you consider ? Locality, Spacious, affordable, Near to Food Joints(Grocery Store), Water facility, security !In a bird eye's view I'd analyse what might be the reasons for India and China being so populous. 1. The vast spread of Plateau region is the main cause as it is easy to live on a plateau rather on Hill or a Desert. 2. As we know, food, shelter and clothing are the basic necessities for any mankind, Here we analyse how the man was able to access them in this location.For Food : As India and China are located close to Tropic of Cancer, where the climate  is generally hot and dry except for easterly coastal areas where orographic rainfall can be very heavy, so the basic food such as fruits,roots and animals are obtained very easily as the trees are of normal height and starch is saved above the ground (again as geographical situations doesn't compel the trees to be long or store/preserve food/water in extraordinary conditions.)For Shelter : Again as there are no extreme climatic conditions, there is no need to have a strong or extra designed houses, so as the rainfall and sunlight is as required, the tree grow well structured and they can be cut to form comfortable houses.For Clothing: As there are no extreme climatic conditions, there is no need to wear a thick woolen clothes. So a normal or any comfortable textile can satisfy this purpose.3. As they are close to Himalayas, the lad of many rivers, people are able to access good and fresh Drinking water.4. Again Himalayas and oceans provide the natural security.5. As the rainfall and sunlight are favorable, the soil formed will be fertile and a variety of crops can be grown, which in turn raise the economy of the people.6. No dense and heavy forests and extreme temperatures(as in Africa), which would let the outbreak of new diseases and kill people. So, As a Man can happily access all his basic needs and can generate economy with minimal effort, I believe that would be his favorite location.

Jagannadh ，生活在印度
任何国家的人口数量都取决于其人口地理位置，温和、舒适的气候条件和水资源。让我详细解释一下，如果我们想搬到一个新的城市或一个新的单位，你会考虑什么基本的东西？地理位置，宽敞，是否负担得起，附近的食品店(杂货店)，供水设施还有安全性！从宏观的角度来看，我下面分析印度和中国人口如此庞大的原因。
1、高原地区广阔的面积是主要原因，因为人们在高原上更容易生活，而不是在山上或沙漠上生活。
2、众所周知，食物、住所和衣服是任何人类的基本必需品，这里我们分析一下人类是如何在这个地方获得这些的。
食物：由于印度和中国靠近北回归线，那里的气候通常是炎热和干燥的，除了东部沿海地区的地形降雨量非常大，所以基本的食物，如水果，根茎植物和动物是非常容易获得的，因为树木有正常的高度，淀粉保存在地面上。
住房：同样，由于没有极端的气候条件，没有必要有一个强大的或额外设计的房子，因此，降雨和阳光是必要的，树木结构生长良好，可以建成舒适的房子。
服装：由于没有极端的气候条件，没有必要穿厚羊毛衣服。所以一件普通或者舒适的纺织品就可以满足这个要求。
3、由于靠近喜马拉雅山脉，这里有许多河流，人们可以获得优质的淡水。
4、喜马拉雅山和海洋再次提供了天然的安全保障。
5、由于降雨和阳光充足，所形成的土壤肥沃，可种植各种作物，这反过来又提高了人民的经济水平。没有茂密的森林和极端的温度(如在非洲) ，而这将会产生新的疾病爆发导致人们死亡。 因此，作为一个人，他可以愉快地获得他所有的基本需求，并且可以用最少的努力产生经济效益，我相信那里会是他最喜欢的地方。

Bill McDonald , Marketing
Geography explains most of the population distribution, and history some of the rest.Both China and India are large countries in area.   They have large areas of land that can be farmed for food.Note that China and India were early civilizations, and started farming for food earlier than many other places that humans have lived.  We can see that today in the extensive variety of Chinese and Indian cuisines - which have the benefit of thousands of years of open source development...There is water for people and farming. Compare with the large nations in the Sahara - Algeria, Mali, Libya, Chad, Sudan - that cannot support many people in this climate cycle.The climate is generally reasonable for most of the country. Compare with Alaska (lots of room, but mostly cold), Canada (more cold, eh ?) and Russia (Welcome to Siberia, land of the future !) ,But humans could migrate to them easily, compared to Australia or Antarctica.

Bill McDonald 、市场营销
地理解释了大部分的人口分布，而历史解释了其余的部分。中国和印度都是地区大国。 他们有大面积的土地可以耕种农作物。请注意，中国和印度是早期文明，开始耕种农作物的时间比人类生活过的许多地方都要早。我们今天可以看到，在中国和印度菜肴的广泛多样性，这有利于数千年的发展...这里有水供人们和农业使用。与撒哈拉大国相比，阿尔及利亚、马里、利比亚、乍得、苏丹在这样的气候中无法支持很多人。气候对这个国家的大部分地区来说基本上是适宜的。相比之下，阿拉斯加(有很多土地，但大部分都很冷)、加拿大(更冷，是吧?）还有俄罗斯(欢迎来到西伯利亚，未来之地!) 但与澳大利亚和南极洲相比，人类可以很容易地迁徙到那里。

Kartikeya Jain , works at The Instrument Society of India VIT Student Chapter
There are a multitude of reasons for this, from civilizations to arable land. But the most important factor in recent times has been: They both are large countries which were colonized and oppressed. Till their independence they both were almost non developing while Europe and America were vis-a-vis an industrial revolution. It is a common phenomena that developed countries have a low population growth rate because they are educated in child planning, protection and in general have max 2 kids. China and india on the other hand have had a 1000% growth in population since the 1950's as these are not yet developed and have little information about family planning.ALso, it is a belief in villagers that more children=better as these countries have labour-intensive farms which have needs people as means of production

Kartikeya Jain ，在印度仪器协会 VIT 学生分会工作
原因有很多，从文明到耕地。但是近代最重要的因素是: 它们都是被殖民和压迫的大国。在独立之前，它们几乎都不是发展中国家，而欧洲和美国面对的是工业革命。发达国家普遍存在人口增长率低的现象，因为他们接受了计划生育、保护儿童的教育，而且一般都最多2个孩子。 另一方面，自20世纪50年代以来，中国和印度的人口增长率达到了1000% ，因为这两个国家尚未发展起来，关于计划生育的信息也很少，村民们相信更多的孩子会更好，因为这些国家有劳动密集型的农场，需要人作为生产资料。

Yash Gupta , Proud INDIAN
This is a consequence of the following situations that were predominant in these countries around mid-twentieth century or mainly the 50’s to 80’s.
* Lack of Education :- Poor level of education was prevailing in these countries. The government focus on education was not at all up to the mark. The youth had no basic information about Family planning. Also, the mentality was quite sick at those times which is no doubt one of the reasons for Child Marriages and other antisocial activities. Sex Education was an out of the world thing at that time.
* Lack of Awareness:- People were forbidden about contraceptive measures like Vascetonomy,. Due to low quality healthcare, education and various other basic life facilities, the adult population had no proper idea of responsibilities to be borne by parents.

Yash Gupta 骄傲的印度人
这是二十世纪中叶或主要是五十年代至八十年代，这些国家普遍存在的下列情况的结果:
* 缺乏教育:-这些国家的教育水平普遍较低。 政府对教育的重视根本没有达到标准。 这些年轻人对计划生育一无所知。 此外，这种心态在那些时候是相当病态的，这无疑是童婚和其他反社会活动的原因之一。 在当时，性教育是一种荒唐的东西。
* 缺乏意识:-人们被禁止使用像输精管结扎术之类的避孕措施。由于医疗保健、教育和其他各种基本生活设施质量低下，成年人对父母承担的责任缺乏正确的认识。

* Uemployment :- Employment levels were on an all time low during those time. But youth is not meant to sit idle, hence they did job but at a wrong place. I hope you understood.
The sudden population explosion is among the primarily reasons behind the declaration of emergency in India during 1975–1977.
In China, the government placed restrictions on the number of children a family can have (One-child polic).

* 就业:-在此期间，就业水平处于历史低点。但是年轻人并不意味着无所事事，他们只是在一个错误的地方工作。我希望你能明白。
突如其来的人口爆炸是印度在1975-1977年期间宣布紧急状态的主要原因之一。在中国，政府限制一个家庭的孩子数量(独生子女)。

Bipin , Indian
1) Two Great Plains :
India and China both have two great Plains. India have Indo-Gangetic plain and China have Great North China Plain.
Look at the world population density map most of the world population lives in these two great Plains. link Population density
Four most populous country China, India, Pakistan, Bangladesh lies in these two great plain. List of countries and dependencies by population
The beauty of these two plain is:
Soothing Temperature: These tropical Plains provide natural vegetation to inhabitant. The temperature do not varies very high or low.Soothing tropical temperature provide comfort to inhabitant in these Plains.
In contrast other great Plains i.e. Great Plains United States great plains is not very good for agriculture and natural life. Most of the land is dry and temperature is too cold.

Bipin 、印度人
1)两个大平原:
印度和中国都有两个大平原。 印度有恒河平原，中国有华北平原。
看看世界人口密度地图，大多数世界人口生活在这两个大平原上。
四个人口最多的国家中国，印度，巴基斯坦，孟加拉位于这两大平原。
这两个平原的美丽支出在于:
舒适的温度: 这些热带平原为居民提供自然植被。温度变化不大，不高也不低。舒适的热带温度为这些平原上的居民提供舒适的生活。
相比之下，其他大平原，如美国的大平原，农业和自然生活条件都不是很好。大部分的土地是干燥，温度太低。

Flat Land : Generally Plains provide comfortable life as compared to mountain. It is very easy to build transport network in plains as compared to desert and mountains. Building houses is very easy in plains.
Arable Land: India and China have world's most arable land. link :Land use statistics by country Alluvial soil provide very fertile land. These lands provide enough food for indigenous people.
Rice Paddies: Rice paddies fed more people. So there direct correlation between total production of rice and population. link : Top 10 Largest Producers of Rice in the World. There is direct correlation between top 10 rice producing countries and top 10 most populous countries.
2) Indian tectonic plate:

平原: 与山地相比，平原通常提供了舒适的生活。与沙漠和丘陵相比，在平原地区建立交通网络很容易。在平原上盖房子也很容易。
耕地: 印度和中国拥有世界上最多的耕地。这些土地为当地人提供了足够的食物。
稻田: 稻田养活了更多的人。因此，水稻总产量与人口数量上有直接的关系。

Collision of Indian tectonic plate with Eurasian plate created great mountains Himalaya. There was a supercontinent called Gondwana. Indian plate split from Madagascar and collide with Eurasian plate.
Himalayan mountains provide natural boundary to save indigenous people from external attack. Indian ocean also provide similar thing. Most of the river originate from Himalaya. River is one of the main reason why population in Indo-Gagnetic plain is so high. Nearly all the rivers in Pakistan and Bangladesh originate from Indian administered Himalaya.
China have Yellow River in great north China plains and Yarlung Tsangpo River in Tibet.

2)印度板块:
印度板块与欧亚板块的碰撞造就了喜马拉雅山脉。有一块超级大陆叫做冈瓦纳大陆。印度板块从马达加斯加分裂出来，与欧亚板块相撞。
喜马拉雅山脉提供了天然的边界，保护当地人免受外来攻击。印度洋也提供类似的保护。大部分河流发源于喜马拉雅山脉。河流是印度恒河平原人口高的主要原因之一。巴基斯坦和孟加拉国几乎所有的河流都发源于印度管辖的喜马拉雅山部分。
中国华北大平原有黄河和西藏的雅鲁藏布江。

Anubhav Dimri , Student at Maharaja Agrasen Institute of Technology (2015-present)
Why only countries like India & China are producing so many people? Why not any other nation?
Every year India adds a population nearly equal to that of Australia's total population And if UP was a nation it would rank 6th among the world in terms of population.
India and China contribute 36.41% to global population.
There are three stages of population growth in every country. Let's understand this by taking example of three different countries at different stages of population growth to make it more clear.
Stage 1- Underdeveloped stage
The country is underdeveloped. The population is very low. Example: African countries like Nigeria , Mauritania,etc.
Now the important point. Low population of these countries doesn’t means that they are not producing people like India or China. Their birth rate is high but because they are underdeveloped, they lack health facilities, sanitation,etc. Result is high death rate, high maternal mortality rates, diseases, epidemics, low life expecrancy, etc which pulls down the effect of high birth rates. Overall Population is very low.
Stage 2- Developing stage

Anubhav Dimri ，马哈拉贾阿格拉森理工学院学生(2015年至今)
为什么只有像印度和中国这样的国家有这么多人? 为什么其他国家没有这么多？
印度每年增加的人口几乎相当于澳大利亚的总人口。如果印度北方邦是一个国家，那么它的人口将排在世界第六位。
印度和中国占全球人口的36.41% 。
每个国家的人口增长都有三个阶段。让我们以三个处于不同人口增长阶段的不同国家为例来理解这一点。
第一阶段：发展不足阶段。
国家不发达。人口很少。例如: 尼日利亚、毛里塔尼亚等非洲国家。
现在重要的一点是。这些国家的低人口并不意味着他们不能像印度或中国拥有那么多的人。他们的出生率很高，但是因为他们不发达，他们缺乏卫生设施，卫生设施等。其结果是死亡率高、孕产妇死亡率高、疾病、流行病和低预期寿命等，这些都拉低了高出生率。所以整体人口非常低。

Development is taking place in the country. Birth rate is still high, but development has lead to improvement in health facilities, diseases are controlled, maternal mortality is reduced, life expectancy is high.This is a great achievement, but overall population starts to increase abruptly. This is the point of Population burst. It is due to illiteracy and lack of family planning awareness among masses. Example: Alomst all developing countries like India, China, Brazil, etc.
The reason India and China contribute to such high share in global population is because they are still in developing stage. See how it increases as health facilities are getting better year by year. Notice that growth rate in the last 6 decades was constant or either decreased.
Stage 3- Developed stage

第二阶段：发展阶段
国家正在发展。出生率仍然很高，但发展已导致卫生设施得到改善，疾病得到控制，产妇死亡率降低，预期寿命提高。这是一项伟大的成就，但总人口开始突然增加。这就是人口爆发的原因。由于群众不识字，缺乏计划生育意识。例如:几乎所有的发展中国家，如印度，中国，巴西等。
印度和中国之所以在全球人口中占如此高的比例，是因为它们仍处于发展阶段。看看它们的人口是如何随着医疗卫生设施的逐年改善而增加的。请注意，在过去的60年里，它们增长率保持不变，或者有所下降。

Country is developed. Literacy is high. As a result of awareness and education, people produce less children. Birth rate goes low, death rate is already low because of highly improved medical facilities. Examples: USA , EU, etc.
Every country aims to control population through the means education and awareness. Once people are aware, population again calms down slowly and India should more aggressively achieve this target.

第三阶段-发达阶段
国家发达。识字率很高。由于识字和教育的结果，人们生育更少的孩子。由于医疗设施的高度改善，出生率下降，死亡率已经很低。 例如: 美国、欧盟等。
每个国家都致力于通过教育和提高认识来控制人口。一旦人们意识到这一点，人口会再次缓慢下降，印度应该更积极地实现这一目标。