The Indus Civilization (Cambridge History of India, Supplementary Volume) c8.3

Language: English

c8.3.1

It is, with all safeguards, sufficiently clear that the rainfall in the Indus zone was somewhat more ample and equable in the third millennium B.C. than it is to-day. Indications from the upland have just been given. On the river-plain, almost the whole terrain, except for the riverine strips and artificially irrigated areas, is now sandy desert with, at the most, a covering of desert-scrub or small bushy trees such as the tamarisk. The subterranean salt, dragged to the surface by the unimpeded evaporation of such moisture as the soil contains, forms a crust which has been well described as "a satanic mockery of snow".¹ It would be hard to imagine a more repelling environment for great cities such as Mohenjo-daro or Harappā, each of these more than three miles in circumference. But we know that in fact their environment was of a very different kind.² The millions of baked bricks of which they are built suggest former vast reserves of local fuel other than scrub though they do not firmly prove this inference; we have to remember that sites on or near the great rivers could be supplied in part by timber floated down, then as to-day, from the Himalayan forests, and it is noteworthy that burnt bricks are especially characteristic of those sites—Harappā, Mohenjo-daro, Chanhu-daro, Sutkagēn-dōr—which are accessible by water, whilst other sites, less accessible, were seemingly content with stone and mud-brick.

c8.3.2

But the very use of costly baked bricks in lieu of the cheap mud-bricks usual in protohistoric Asia may be supposed to reflect a climate wet enough to necessitate the more durable material.¹ The Indus seals, with their vivid representations of tiger, buffalo, rhinoceros and elephant, are the work of artists to whom these marsh- or jungle-animals were familiar; alternatively, the extreme scarcity of evidence for the camel (p. 60) is consistent with non-desert conditions. The mere existence of the cities is indeed conditional upon a local fertility out of all relation to the present landscape and not wholly explicable by the possibility of elaborate former irrigation systems of which not a trace can be expected to survive on the present aggraded surface. A certain degree of climatic change is beyond dispute; but how far that change is due to "natural causes" and how far to sheer human improvidence (if that be other than a "natural cause") is less easy to say. History would suggest that the process of desiccation was already far advanced by the time of Alexander the Great, whose returning army was decimated in the cheerless wastes of Makrān. And it may be that an increasing aridity had already contributed to the downfall of the Indus cities. When we turn from fact to cause, difficulties accumulate.

c8.3.3

The present aridity may have been induced wholly or in part by a northward movement of the Atlantic cyclones, on the hypothesis that these were at one time deflected southwards to the latitude of northern Africa and extended to Arabia, Persia and India. Or it may be that the south-western monsoon then touched the Indus valley. We do not know. In Algeria a similar and perhaps indeed related problem confronts the student of the Roman remains which now lie derelict in a desert environment, and there is a wide agreement that man rather than unaided climate has there been responsible for the deterioration.² In central Asia, Aurel Stein, who was always attracted by this problem in his far-flung fieldwork, similarly regarded destructive barbarian inroads as the major cause. On the other hand, in Kalāt and Makrān the phenomena left him in some doubt as to the bias of the evidence; at one point he observes that the evidence "distinctly pointed to the local climate having undergone a great change since chalcolithic times in its effect upon cultivation", whilst elsewhere he remarks upon an agricultural decadence, even in the vicinity of water, "illustrating once more how in an arid land human factors can within certain limits produce results which centuries hence might easily be mistaken for those of true 'desiccation'".³