How can we explain the fact that 40 percent of the world lives in only two countries, China and India? How did these two civilizations manage to amass such a large population relative to other civilizations?
世界上40%的人口都生活在中国和印度这两个国家，这个现象该如何解释？相较于其他文明，这两个文明是如何积累如此庞大的人口的呢？
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Balaji Viswanathan
Abstract:
概要：
India and China together hold 20% of world's arable land (land suitable for a major crop), producing 50% of the world's rice and 30% of the world's wheat. They are spread around the Tropic of Cancer (a great zone for human settlement), were unified multiple times in the past (leading to a large land area under one flag), got to the major cereals earlier (rice & wheat), got the benefit of other civilizations nearby (borrowing ideas of wheel & writing systems) and were spared from many of the major human calamities & migrations of history.
印度和中国总共拥有全世界20%的可耕地(适合种植主要作物的土地)，种植了世界上50%的水稻和30%的小麦。这两个国家都分布在北回归线附近(是人类定居的一大地区)，历史上被多次统一(因此领土很广袤)，较早开始种植主要的谷物(水稻和小麦)，也受到附近其他文明的惠泽(借鉴了车轮和文字体系)，也没有经历过历史上多次重大的人类灾难和迁徙。
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.
首先，我要先快速澄清一个错误的观点。有些人认为印度在上个世纪经历了一场失控的人口灾难。但事实是，印度目前在世界人口中所占的比例远远低于其历史水平，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数据。
How come India and China accounted for close to 60% of human population at various points of time in history?
为什么印度和中国在历史上多数时间都占到全世界近60%的人口？
Climate and Geography:
气候和地理条件：
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 Mexco, central Australia, Central Asian Republics are too few. This rules out a sizeable chunk of earth's land for dense human settlement.
尽管印度和中国“只”占据了地球陆地面积的十分之一，但两国在地球宜居土地上的占比却接近四分之一。地球上的大片区域并不适合人类居住——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、亚马逊雨林和非洲中部。蒙古、墨西哥北部、澳大利亚中部、中亚共和国的水资源太少。这就排除了地球上一大块适合人类密集居住的土地。
The region around the Tropic of Cancer and the Tropic of Capricorn is the best suited for human settlement (see below). A big chunk of this region is lost in the Sahara, leaving India, Mexco, Southern US & China as the major non-arid regions on this zone. In the southern hemisphere most of this critical zone is taken over by oceans or deserts (Kalahari, Great Victoria, Atacama).
北回归线和南回归线周围的地区最适合人类定居(见下文)。该地区的一大部分都被撒哈拉沙漠吞没，印度、墨西哥、美国南部和中国是该地区主要的非干旱地区。在南半球，这一地带的大部分也被海洋或沙漠(卡拉哈里、大维多利亚、阿塔卡马)占据。
Water and Silt:
水和泥沙：
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.
现在让我们来看看北纬30度左右(北回归线以北)的关键地带，所有主要文明都在这里兴起，几乎所有现代宗教都来自这里。这个纬度附近的人们塑造了古代世界的历史。
While Iran (between purple and brown area below) had civilizations going from the ancient era, it never had any major river to support a massive population growth. Israel (between the green & purple) 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.
虽然伊朗(下图紫色和棕色区域之间)很早就拥有了文明，但它没有大型河流来滋养大规模的人口增长。以色列(绿色和紫色区域之间)太小了，外敌不断。埃及处在狭窄的尼罗河谷之外，伊拉克的大部分地区(特别是远离底格里斯河和幼发拉底河的地区)和阿拉伯半岛的大部分地区都太过干燥炎热，无法供养大规模的人口。
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.
印度北部和中国东部坐落在印度河+恒河+雅鲁藏布江和黄河+长江等河流形成的巨大冲积平原上。最早有文字记载的人类文明就出现在这些河谷平原上，以及尼罗河(埃及)和幼发拉底河(现代伊拉克)所创造的平原。这些河谷为文明提供了适宜的条件，提供了农业种植所需的水和泥沙，适宜的气候条件和适合商业发展的河流。
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.
世界上这样的大河谷屈指可数，尤其是在这个纬度。总的来说，全世界大约有26个主要的河流流域(见下图)，其中只有16个位于宜居地区。印度和中国占据了这16个中的4个。在剩下的12个中，有5个被广阔的热带雨林所包围。其中三个：奥兰治，墨累-达令和密西西比州的位置有些偏僻，无法滋养出大型文明(但也滋养了独特的本土文化，现在也是大城市的所在地)。这使得尼罗河、多瑙河、幼发拉底河、赞比西河成为印度和中国以外的主要文明摇篮。
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. The following river map is unusual among any country in this zone and enabled multiple regions of population concentration.
除主要河流外，中国流域面积达到100平方公里及以上的河流多达5万条。印度的河流数量较少，但全国各地均有分布。这些河流比不上亚马逊河那样庞大，但也不至于小到无法养活人口。
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.
简而言之，印度和中国有多个河流水系，既庞大又宜居，带来了巨大的粮食产量。印度和中国都不依赖于单个河流水系（如埃及），各自都拥有3个以上的大型河流水系。
Food production:
粮食生产：
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.
2005年，印度和中国总共拥有全世界20%的可耕地（适合种植主要农作物的土地），生产世界50%的水稻和30%的小麦，详见各国土地使用统计数据。
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.
但这一比例在两个世纪前还要高上许多，当时巴西、西伯利亚、澳大利亚和美国的大片土地还没有被开发出来。印度有50%的土地是可耕种的，而澳大利亚、加拿大或俄罗斯即便引进现代农业技术，也只有不到7%的可耕种土地。
Remember that food and water were the most critical for previous civilizations. But, by then the drop in fertility rates and migration restrictions made population growth slow in the US & Europe.
记住，对以前的文明而言，食物和水是最重要的。但是，那时生育率的下降和移民限制使得美国和欧洲的人口增长速度十分缓慢。
Connectivity & Idea sharing
互通互联与知识分享
Mississippi had a nice river valley system that was in the same latitude & had all the right climatic conditions (other than the hurricanes & typhoons). Indeed it supported a rich Native American culture. However, it never had the population density of Ganges or Yangtze river valleys.
密西西比州有着良好的河谷网络和适宜的气候条件(不同于其他地区飓风和台风频发)。事实上，这里滋养了丰富的美洲原住民文化。但这里从未达到过恒河或长江流域的人口密度。
One reason could be the fact that humans migrated there much later than in Asia (12,000 BC vs. 70,000 BC) leaving them less time to succeed in a trial-and-error manner.
其中一个原因可能是人类迁移到此处的时间比亚洲晚得多(公元前12000年 vs 公元前70000年)，导致他们没有那么多可以通过试错获得成功的时间。
Size & Organization
领土面积与组织机构
Joseph Boyle brought an important point that both India and China are massive (with a massive chunk of tropic/subtropic land). India and China are dense as well as huge. Parts of western Europe and Southeast Asia have density comparable to India & China, but was not unified for a sufficient period of time.
约瑟夫·博伊尔提出了一个重要的观点：印度和中国十分庞大(拥有大量的热带/亚热带土地)。印度和中国人口密集，幅员辽阔。西欧和东南亚部分地区的人口密度与印度和中国相当，但国家统一稳定的时间不够久。
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. Since then, the Chinese had been unified under the Yuan, Ming and Qing dynasties while India had been unified under the Mauryas, Guptas, Mughals and later the East India company. (Coincidentally both Mughals and Qings — the last native empires of India & China were outsiders who got assimilated into the respective cultures).
自公元前200年以来，印度和中国都很幸运地实现了较长时间的国家统一。秦朝在公元前206年统一了中国，阿育王在公元前250年统一了印度。从那时起，中国历经元、明、清三个王朝的统治，保持了国家的统一，而印度则在孔雀王朝、笈多王朝、莫卧儿王朝以及后来的东印度公司的统治下保持了国家的统一。(巧合的是，印度和中国最后的帝国莫卧儿王朝和清朝王朝都是外来者，都被各自的文化同化了)。
Crops & food
农作物与粮食
Europe's population exploded when potato was brought back from the New world 500 years ago. Ireland and other countries rapidly grew as they had little food option before. That's how important a staple crop is.
500年前，当人们将马铃薯从新大陆带回欧洲时，欧洲人口出现了激增。爱尔兰和其他国家的人口迅速增长，在那之前他们几乎没有什么食物选择。这就是主食作物的重要性。
China domesticated Rice in about 10,000 BC and rice quickly moved to South & Southeast Asia. At about the same time, Wheat was domesticated and moved from West Asia towards India. Thus, both India and China had access to massive cereal crops.
中国大约在公元前10000年驯化了水稻，水稻迅速传播到南亚和东南亚。大约在同一时期，小麦被驯化并从西亚向印度传播。因此，印度和中国都可以种植出大量的谷物作物。
In contrast, both Europe and Africa had relatively less access to major cereals. Major cereals reached Europe relatively late and until recently Africa had no major cereal group that lent itself to massive farming. Even today, Africa's cereal yield outside of Nile valley and South Africa is very poor.
相比之下，欧洲和非洲获得主食谷物的机会相对较少。主食谷物传入欧洲的时间相对较晚，直到最近，非洲还没有适合大规模农业生产的谷物品种。即使在今天，尼罗河谷和南非以外的非洲谷物产量也很低。
Major epidemics, migrations & wars
大型传染病、移民和战争
In 540 AD the Plague of Justinian ravaged Europe and decimated cities like Constantinople. 50% of Europe perished in that plague. In 1346 the Bubonic plague (Black Death) killed 30-60% of all Europe. While those affected India and China too, the percentage of deaths was less. Between 16th and 19th centuries sizable parts of Europe emigrated to the Americas, Africa, Asia and Australia. The World Wars and the drop-in fertility in the 20th century (with better education) kept Europe's population further in check.
公元540年，查士丁尼大瘟疫席卷欧洲，摧毁了像君士坦丁堡这样的城市，50%的欧洲人死于这场瘟疫。1346年，黑死病夺走了欧洲30-60%的人的生命。虽然印度和中国也受到了影响，但死亡比例较低。在16世纪至19世纪，大批欧洲人移民到了美洲、非洲、亚洲和澳大利亚。世界大战和20世纪生育率的下降(随着教育水平的提高)使欧洲人口进一步受到抑制。
Iran lost 90% of its population in the Mongol invasion of Central Asia.
Native Americans were decimated by Small pox and other old world diseases brought by European settlers.
蒙古人入侵中亚时，伊朗90%的人口丧生。
美洲原住民因欧洲殖民者带来的天花和其他旧世界疾病而大量死亡。
While China had some major disasters (such as the Mongol invasion and plague) its population was sizable enough to recover from them & was fairly sparred since 1300s. India escaped Genghiz Khan's warriors and the Bubonic plague. Until the coming of famines under the East India Company, major death tolls were relatively uncommon.
虽然中国经历过一些重大灾难(比如蒙古入侵和瘟疫)，但由于人口基数足够庞大，可以从灾难中恢复。印度躲过了成吉思汗的铁骑和黑死病。在东印度公司统治时期的饥荒降临之前，人口大规模死亡的情况并不多见。
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为什么印度农业没有像美国那样现代化，印网民：耕地面积是中国的好几倍，粮食产量却比中国更少