| Contemplation of the huge numbers of people now living in South Asia prompts me to point out that this volume deals with about 20 percent of the world's population (which stood at almost 5 billion in 1986, the year in which the population of South Asia passed the 1 billion mark). The rough geographic limits encompassing this mass of people and cultures are the Helmand River in the west, the Chindwin River in the east, the Indian Ocean to the south, and the Tibetan reaches of the Brahmaputra River to the north. We have not treated Tibet as a part of this territory, as it is today administered as a province of China, and it is not included in the population estimates given below. For convenience, however, Mauritius has been dealt with in this volume.
The land area covered by this volume is 4,430,789 square kilometers (not including Mauritius, Afghanistan, or Tibet). The average population density at present is about 260 persons per square kilometer, although this figure rises to around 155,000 persons per square kilometer in parts of Bombay and Calcutta, the two largest cities. However, there are some extensive tracts with very light population, notably the Thar Desert, the Himalayan Mountains, the Karakoram and the Hindu Kush (see map 2).
If there is a single factor uniting geography and culture throughout tropical Asia, it is that much of eastern India, Bangladesh, Sri Lanka, and in general the lowland areas of Southeast Asia are devoted to the intensive cultivation of one staple crop, rice (Oryza sativa). Evidently it was indigenous to southern China and Vietnam but spread south and west from there during the Neolithic period, until in ancient times it had occupied most of the land suited to its cultivation in the tropical areas, which up to that point had been densely forested. Today, while large tracts of that tropical forest do still remain in some parts of Southeast Asia that are unsuited to rice, many thousands of square kilometers in the formerly forested Gangetic Plain have become small irrigated paddy fields, terraced in the hillier parts to make use of the slopes.
Because of its growing needs rice is ideally suited to these tropical forest lands: unlike any other cereal crop, rice needs a hot growing season, inundation of the field during part of the growth period, and hence an abundant supply of water from rivers or heavy rainfall. The two monsoons answer this need fully. Where irrigated paddy is grown, one finds the densest rural populations in the world, as for example in Kerala State and Bangladesh. Cultivation of the crop is labor-intensive, using humans even more than it does water buffalo. |