Such a ratio would give a total population of four million for the entire territory of the Indus civilisation, or nearly six persons per square kilometre.
This would compare with nearly 50 persons per square kilometre in the same area in 1901. In 1991 the corresponding figure was about 180 persons! The comparison helps us to see how sparsely populated the Indus basin must still have been at the time of the Indus civilisation”.
In a region which did not have sufficient rainfall for supporting agriculture recourse was taken, as has been noted above, to the flood-plains of the rivers which had the tendency of depositing every year soft and fertile alluvial soil along their banks during the summer months.
The agricultural pattern of Indus civilisation was thus geared accordingly and it is useful to understand the river behaviour at some length to truly appreciate this feature. The Indus has a very large and wide flood plain and the alluvium deposit too is fairly deep. In fact the behaviour of Indus is comparable with the two other river systems that were also the cradle of important ancient civilisation the Nile and the Euphrates Tigris river systems.
A comparison of this type may help us place the Indus system in proper perspective. A comparison of Indus with Nile and Euphrates Tigris has been done by Shereen Ratnagar. She writes: “The Nile is, in contrast to Indus, predictable and tame.
It floods its extremely narrow valley between late June and September with a fair degree of regularity, the water standing in the fields for several weeks and then subsiding, thoroughly wetting and fertilizing the soil before it is time to sow. Wheat and barley require no further irrigation, even though Egypt is a hyper-arid land with less than ten centimetres of rainfall per year.
“The Indus too floods in the summer months, well before the wheat and barley sowing. It is at its highest level in August. But its annual water discharge is 207 billion cubic metres as against the 63 billion cubic metres of the Nile. Its catchment in the Himalaya is several times the magnitude of the Nile or Euphrates catchment, and it carries a huge amount of water at great speed”.
The flood plains of Indus, as is evident, were quite expansive and the alluvial deposit sufficiently deep for supporting agriculture, mainly the rabi crop, for the vast habitation settlements as that of the Indus civilisation. Shereen Ratnagar is quite perceptive when she says, “The locations of Harappan sites are not totally explained by climatic conditions.
In fact rainfall, as in all arid regions of the world, is erratic variability in Sind, for example, is 65 per cent. In ancient economics the aim was to minimise risk rather than to calculate the relative costs of input and output, for land and labour were not commodities that were bought and sold – much less so seed, fodder or natural fertilizer.
Hence people chose to settle in areas with reliable resources – i.e. those annually inundated or, more important, with perennial springs or lakes or sweet-water wells close to the surface – rather than in areas with high but unreliable rainfall. It is truly a paradox that the plains of the mighty Indus did not offer potential for unlimited agricultural growth”.
The important evidence on agricultural tools comes from Kalibangan, Banwali, Jawaiwala and Shortughai. Two ploughed fields have been discovered by archaeologists from Kalibangan and from the Indus settlement at Shortughai.
The sites at Banwali and Jawaiwala (in Bahawalpur, Western Punjab) have provided evidence relating to plough as an agricultural tool. The discovery of plough furrowed field at Kalibangan is of seminal significance as it proves the use of plough and the use of ox for drawing the plough as a draught animal.
The use of plough and ox as a draught animal for drawing the plough was a fundamental advance in agriculture. Irfan Habib notes its significance by asserting that the “plough greatly lessened the labour of peasants previously performing the same task manually with the hoe, and also enabled the same family to till a much larger area of land (probably double, to judge from studies of such change in contemporary sub-Saharan Africa). It accordingly brought about a substantial increase in yield per head of population”.