The final centuries of the Harappan civilization in the early second millennium saw a decline in civic standards in many settlements, including the cities of Harappa, Mohenjo-daro, and Dholavira. Drains were not maintained and inferior houses were put together, often from salvaged bricks. Heavy industry, including pottery kilns and metal furnaces, appeared in what had formerly been residential houses, and the Pillared Hall on Mohenjo-daro's citadel was divided into workshops. The breakdown of civic life seems particularly marked at Mohenjo-daro, where dead bodies were given perfunctory burial in disused houses or streets. In many settlements, concealed hoards of valuables whose owners never returned to reclaim them reveal a climate of insecurity.
The internal distribution system that had integrated the state began to break down, each region gradually coming to rely on its own resources and local trade networks. Regional cultures emerged, with many material similarities to the local Early Harappan cultures of half a millennium before; some regions flourished while others, notably Sindh, declined further. Writing and weights no longer served a purpose and were abandoned. Gujarat continued overseas trade but was linked internally with western India instead of with the Harappan realms. In the east, the Saraswati Valley was becoming depopulated as settlers spread toward the Ganges-Yamuna doab.
The disintegration of the Indus civilization, the abandonment of settlements in some areas, and the subsequent disappearance of its culture are in stark contrast to other early civilizations, which were generally replaced by their rivals or developed new foci but rose again. When civilization reemerged in India, it was in quite a different area, on the Ganges, where civilizations continued to rise and fall for the rest of South Asia's history. The causes of the Indus collapse are still not completely known but some possible factors have been isolated.
Health
One reason for the urban decay at Mohenjo-daro was probably the poor health of its residents. Skeletons from the upper levels, deposited in abandoned houses or streets, were in the past interpreted as victims of warfare (identified by Wheeler as Indo-Aryan raids), but studies have shown their fate to have been quite different. No traces of violence were found on the bones of these famous "massacre victims," with two exceptions, and in both cases the injuries were suffered well before death. Instead, the skeletons showed signs that many individuals had suffered from malaria, spread by mosquitoes probably breeding in flooded land near the city. Mohenjo-daro's residents may also have suffered from cholera. Seepage of wastewater from the drains may have contaminated drinking water in the numerous wells, and a few cases could have escalated rapidly into a major epidemic.
Environmental Problems
Many possible natural and humanly induced disasters have been suggested to account for the collapse, some of them sudden and dramatic, others long-term and insidious. For example, it is possible that the monsoon winds may have shifted slightly southward, decreasing critical rainfall in some areas, causing drought, and increasing it in others, causing flooding. Opinions and evidence on this matter, however, ebb and flow with the years, and we still cannot say for certain whether such a change took place and, if it did, whether it contributed to the Indus decline.
Climate Change. The late third millennium BCE saw a global increase in aridity that had a serious impact on the civilizations of Egypt and Mesopotamia and on the Harappans' neighbors in Seistan. The effect in the Indus region was to decrease the reliability of the summer monsoons, and, paradoxically, to increase winter rainfall, neither of which had a serious impact on Harappan agriculture, although it may have encouraged diversification. Nevertheless, recent studies of soil samples from Harappa suggest that this global dry period had a longer-term effect on vegetation and landscape in the region, possibly contributing to population decline and the abandonment of settlements in the period 1900-1600 BCE.
Environmental Degradation. It has been suggested that firing the huge number of baked bricks used in Harappan settlements would have entailed massive deforestation. However, recent investigations have shown that the scrubby vegetation of the Indus Valley would have been a sustainable source of fuel adequate for this purpose. Perhaps more serious was the quantity of fuel used in industry, especially metalworking, but also making pottery and faience. An unknown volume of timber was also felled for domestic construction and for export. Agriculture may also have taken its toll. Limited evidence of environmental degradation exists in some areas such as Gujarat, where the shift to scrubby acacia wood and dung for fuel in the Late Harappan period implies significant earlier deforestation.
The Coastline. Sea levels began falling in the late third millennium, leaving Harappan ports in the Makran high and dry. This must have had a major impact on trade passing through the Makran. In Saurashtra, Lothal lost its access to the sea, and the port of Kuntasi was abandoned around 1700 BCE. On the other hand, a new port was established at Bet Dwarka on the northern peninsula of Saurashtra, a spot exposed by the receding coastline (and today again under water).
The Gujarat coastline was also affected by the deposition of enormous volumes of silt by the Indus and other rivers then debouching into the Ranns of Kutch, transforming them gradually from open water to salty marsh, though the extent to which this had occurred by the last centuries of the Mature Harappan culture is unknown. It is likely to have been enough by that stage to cause inconvenience to shipping, creating hazardous stretches of shallow water and forcing the closure of some established sea lanes. It is possible that the vicissitudes of Dholavira (which was temporarily abandoned in the twentieth century BCE) were attributable to difficulties of access by sea.
The Indus River. The Indus region is prone to earthquakes and their effects have been observed in several settlements, including Mature Harappan Dholavira and Early Harappan Kalibangan. No major earthquake damage, however, has been noted in settlements around the time that the decline set in. Eruptive mud from tectonic activity has in recorded times occasionally dammed the Indus, causing massive but short-lived ponding and flooding. However, there is no convincing evidence that Mohenjo-daro experienced major and prolonged flooding in the critical period.
The Indus has changed its channels many times, and sometimes there has been a major shift in its course; the river today flows much farther east than in the Harappan period. However, major flooding and river course changes in the Indus plains were a regular hazard of life, with which the Harappans had learned to cope when they first colonized the plains: Major settlements were constructed on massive platforms, while villagers in the floodplain may have managed by occupying houseboats for all or part of the year.
The Saraswati Valley. In contrast, changes taking place in the Saraswati Valley in the early second millennium were probably a major contributor to the Indus decline. In Harappan times, the Saraswati was a major river system flowing from the Siwaliks at least to Bahawalpur, where it probably ended in a substantial inland delta. The ancient Saraswati River was fed by a series of small rivers that rose in the Siwaliks, but it drew the greater part of its waters from two much larger rivers rising high in the Himalayas: the Sutlej and the Yamuna. In its heyday the Saraswati appears to have supported the densest settlement and provided the greatest arable yields of any part of the Indus realms. The Yamuna, which supplied most of the water flowing in the Drishadvati, a major tributary of the Saraswati, changed its course, probably early in the second millennium, to flow into the Ganges drainage. The remaining flow in the Drishadvati became small and seasonal: Late Harappan sites in Bahawalpur are concentrated in the portion of the Sarawati east of Yazman, which was fed by the Sutlej. At a later date the Sutlej also changed its course and was captured by the Indus. These changes brought about massive depopulation of the Saraswati Valley, which by the end of the millennium was described as a place of potsherds and ruin mounds whose inhabitants had gone away. At the same time new settlements appeared in the regions to the south and east, in the upper Ganges-Yamuna doab. Some were located on the palaeochannels that mark the eastward shift of the Yamuna. Presumably many of the Late Harappan settlers had originated in the Saraswati Valley.
Changing Agricultural Regimes
During the Mature Harappan period, the staple crops—wheat, barley, and many pulses—were winter sown. Rice, a summer crop, was known but apparently little used until the early second millennium. Native millets, also grown in summer, were the main crops in Saurashtra but were low yielding. However, in the early second millennium much higher-yielding African millets (sorghum, finger millet, and pearl millet) were introduced and began to be cultivated. These new crops now made it economical to invest time and effort in summer (kharif) cultivation.
During the Mature Harappan period, Gujarat was an area of low agricultural productivity, and many of its inhabitants engaged part - or full-time in other activities such as trade by land and sea, shellworking and beadmaking, fishing, and salt making, supplying goods and materials to other Harappan realms and receiving the means of subsistence. The cultivation of African millets, by greatly increasing productivity, brought about an agricultural revolution on Saurashtra during the early second millennium, with a massive increase in the number of settlements; some, such as Rojdi, were far larger than before. The new prosperity of Saurashtra offered Gujarat a local market, weakening its need to be integrated into the Harappan internal distribution system. Gujarat's opting out would have had serious repercussions for the organization of the state.
At the cost of an increase in labor, two crops could now be raised each year in areas where both the old and the new crops could be grown. These included the Kachi plain, where rice now became an important crop. Since rice required irrigation, this implies a considerable labor investment in the creation of permanent irrigation systems. The millets were tolerant of arid conditions and were therefore well suited for cultivation in marginal areas that had previously only provided rough grazing. The millets could be used both as human food and as fodder for domestic animals.
Rice also began to be grown in the eastern Indus zone. This proved important in facilitating the gradual spread of farming communities into the northern part of the Ganges region.
Outside Contacts
Sea Trade. The importance of overseas trade to the Harappans is uncertain. It has been suggested that the disruption of direct trade with Sumer due to political changes there around 2000 BCE may have had an impact on the Harappan state. This, however, seems unlikely since trade continued, albeit on a reduced scale, through the entrepot of Dilmun until the mideighteenth century BCE, when Sumer suffered economic collapse, by which time the Harappan state was itself already in decline. The loss of the Makran ports, due to the falling sea level, and the collapse of the Harappan state put sea trade into the hands of the Late Harappans in Gujarat, who continued to profit by some trade with Dilmun and Magan until at least 1600 BC.
Overland Traders, Raiders, and Settlers. In the early second millennium, people from the BMAC in Bactria and Margian expanded into adjacent regions, including Seistan, from where they penetrated the Indus region or traded with its inhabitants. This took place, however, after the Indus decline had begun: BMAC material occurs in Baluchistan, in Pirak and other sites on the Kachi plain, alongside Cemetery H material at Harappa and Jhukar material in Sindh, and in the Gandhara Graves in Swat, as well as much farther south at Gilund in Rajasthan. The physical diversity of the skeletons from the final period at Mohenjo-daro suggests that some were outsiders. Burned settlements in Baluchistan suggest that the newcomers came as raiders rather than as traders, though there is little evidence that this was also the case in the Indus region.
Linguistic evidence indicates that Proto-Indo-Iranians, pastoral nomads from the steppe, spent some time in contact with the BMAC. Later groups of their Indo-Aryan-speaking descendants began to appear in the northern part of the subcontinent, including Swat. The most apparent archaeological trace of their arrival is the appearance, for the first time in the subcontinent, of domestic horses. They began to penetrate the Punjab some time between 1700 and 1500 BCE, well after the disintegration of the Harappan state.
Summary
The decline of Harappan urbanism probably had many contributing factors. The shift to a concentration on kharif cultivation in the outer regions of the state may have seriously disrupted established schedules for craft production, civic flood defense, building and drain maintenance, and other publicly organized works on which the smooth running of the state depended. The reduction in the waters of the Saraswati and the response of its farmers by migrating into regions to the east tore apart the previous unity of the Harappan state, disrupting its cohesion and its ability to control the internal distribution network. At the same time, Gujarat may have been asserting its independence. The poor state of health of Mohenjo-daro's citizens can have done nothing to improve the situation: decline there would have seriously affected the management of the internal communications networks, particularly along the Indus. The state organization crumbled away, leaving behind a series of flourishing regional communities in Gujarat, the Kachi plain, and the Punjab/eastern region, but undermining the infrastructure that had held together the urban way of life.
World History
