The Harappan Civilization of South Asia, ca. 2500 to 1900 B.C.E.,
was a period of intense urbanization. In the archaeological record, a
unique assemblage of material artifacts represents this culture. We
first see this assemblage and urbanization in the Indus Valley ca.
2500 B.C.E. It spreads widely, and suddenly disappears six centuries
after its first appearance. After six centuries of use and massive
economic investment, why were these cultural norms abandoned? Why a
sudden and complete abandonment?
Archaeologists have proposed numerous models to explain the
collapse of the Harappan Civilization. Floods, invasions, earthquakes,
and climatic change have all been proposed as answers. I do not
believe that any current proposal is completely convincing. The
evidence for each is limited to a single small area or locality, and
is then imposed as a universal answer upon the entire civilization.
In an attempt to answer the question of why the Harappan
Civilization collapsed, I will first give a brief summary of the
Harappan Civilization. Next, I will describe what is meant by collapse
and what portions of society ‘collapsed.’ Third, I will summarize the
four primary hypotheses previously proposed. Finally, I will attempt
to synthesis a new and broader hypothesis to explain the collapse of
the Harappan Civilization
At the same time as the Old Kingdom of Egypt and the Early Dynastic
Period of Mesopotamia, an extensive and complex civilization dominated
South Asia. Called the Harappan Civilization, it extended temporally
from 2500 to 1900 B.C.E. A time of homogenization, exemplified by the
adoption of a particular artifact assemblage. This assemblage
included: a single unique script, a recognized and broadly utilized
iconography, large buildings of uniform baked brick, stoneware, broad
use of copper/bronze, urban drainage systems, and broad use of the
Harappan Decorated Ware.
The Harappan Civilization was located in northwestern South Asia.
The primary core was located in modern Pakistan along the Indus River
and its tributaries. The secondary settlement included the rest of
Pakistan, and much of northwestern India, including: Gujarat, Punjab,
Hary~na, and Rajasthan.
Fingers of secondary and peripheral settlement extended along the
Makran Coast, through the passes into Afghanistan, Iran, and
Turkmenistan, along the Gangetic Plain half way through Uttar Predesh,
and down the west coast of India as far as Mumbai.
The Mature Harappan was a time of intense economic and trade
activities. These activities were supported by the extensive use of a
uniform writing system, weights, and linear measures. The script was
logographic in nature and contained more than 500 signs. This script
appears to be unrelated to any other system and died with the collapse
of the Harappan Civilization. The Harappans utilized a base eight
system for numeration and a binary system for weights.
A complex system of trade networks made the Harappans rich and
guaranteed access to exotic goods. Internal networks moved every
imaginable good throughout the Civilization. Shell, dried fish, and
pearls from the coast; copper, tin, chert, precious metals and
semiprecious stone from the hill country; and grain, animals, and wood
from the rural areas flowed from one area to another, resulting in a
nearly homogenous distribution of goods across the face of the
civilization irrespective of origin. Networks extended into Central
Asia, Mesopotamia, and the Arabian Peninsula. These networks exported
every good and luxury available in the Harappan Civilization. It is
unclear what was being imported, but it is likely to be wool cloth,
fish, and grain.
The Harappan Civilization utilized a diverse assemblage of wild and
domestic plants in the production of food and industrial products.
Animal production centered on zebu cattle, buffalo, sheep, goats,
fish, chicken, and some wild species. Agricultural foods were produced
through two means of production. Crops of barley, wheat, oats,
lentils, chick and grass peas, jujube, and mustard were sown in
autumn, harvested in spring, and watered by winter rains. In the
second, crops such as millits, sorghum, rice, cotton, and dates and
were sown in the summer to be watered by the summer monsoon and
harvested in the fall. As time passed the people of both areas
diversified and intensified their food production by incorporating
Urban centers of the Harappan Civilization were large and
sophisticated. They were well planned with separate domestic and
public space, each demarked into efficient areas of action. In
domestic areas numerous wells, broad strait, streets, and an expansive
system of public sanitation, are indicative of Harappan
foresightedness and political control. Public areas were ritual and
secular; each with its own designated location. Several areas of
manufacture were designed for, the resident trades evidently were
decided by the amount of pyroclastic activity necessary for completion
of the good. Goods produced as a result of advanced craft activities
and specialization include: complex stone beads, fine and coarse
ceramics, copper/bronze tools, faience, seals, shell and clay bangles,
clay figurines, stoneware. The Harappans developed fine and
distinctive art: jewelry, masks, seals, stone and cast bronze
sculpture, and ceramic figurines.
When we consider the reasons for the collapse of the Harappan
Civilization, we must first define what did change and what, if
anything remained static. Most basic to any culture are the people.
Possehl reports a clear and consistent occupation of sites from the
Mature through the Late Harappan (Possehl, 1982). The genetic evidence
shows there was little population change early in the second
millennium B.C.E. (Hemphill, Lukacs and Kennedy, 1991).
The deurbanization period of the Harappan Civilization saw the
collapse and disappearance of the urban phenomena in the South Asia
for the next seven centuries. The theme for this period is
localization. Significant change in the cultural assemblage did occur.
Architectural and ceramic forms changed along with the loss of
writing, planned settlements, public sanitation, monumental
architecture, seaborne and exotic trade. seals, and weights (McIntosh,
2002). At this time a small but visible population influx occurred
from Afghanistan and Baluchistan. The continuation of local and
regional polities from the Early through the Post Harappan seems
evident; that which had integrated and united the area disappeared.
Archaeologists have offered four primary and competing explanations
for the collapse of the Harappan Civilization. Three are based on
ecological factors: intense flooding, decrease in precipitation, and
the dessication of the Sarasvati River. The fourth hypothesis is that
of the Aryan Invasion, proposed by Sir R. E. Mortimer Wheeler and
Stuart Piggott (1953 and 1950). It was based on a diffusionary model
of a mass invasion of Indo-Aryan peoples swarming into and destroying
the civilized Harappan Civilization. There is no good evidence to
support this conclusion: no destruction levels, mass graves, or large
The first ecologically based model is that of flooding. First
proposed by hydrologist Robert L. Raikes (1964), this model suggests
that a natural dam developed to the south of Mohenjodaro near Sehwan.
Raikes saw evidence for massive flooding at Mohenjodaro and proposed
this model in response (Raikes, 1964). R. J. Wasson (1987 and 1987)
argued that the unconsolidated alluvial sediments of the Indus
floodplain would not have withstood the pressure of such extensive
The second and more widely supported model is that of desiccation
caused by a decrease in precipitation. First proposed Sir John
Marshall (1931) and later expanded by Wheeler (1953), the model was
based not on some empirical measure of environmental change; but, upon
a flowed analogy drawn from the archaeological evidence. They felt
that the Harappan Civilization was a subset of a larger riverine group
including Egypt and Mesopotamia (Possehl, 2002). Cultural traits, such
as the extensive use of baked brick instead of mud brick, elaborate
civic drainage systems, and wet environment animals (elephants,
tigers, rhinoceri) represented on art and seals were considered proof
of a wetter environment than today (Possehl, 2002).
G. Singh (1971) proposed environmental evidence in support of the
‘dessication hypothesis’. He looked at the changing salinity of three
lakes in Rajasthan, India as expressed in pollen cores. He saw a
salinity increase in the beginning of the second millennium B.C.E.
(Singh, 1971). From this he deduced a precipitation decreases and
proposed this decrease as the primary contributing factor in the
collapse of the Harappan Civilization. Currently both saline and fresh
water lakes dot the Rajasthan landscape (Possehl, 2002). The salinity
of such lakes are determined by the amount of subterranean drainage (Possehl,
2002). Whether these drains are open and allow salinated water to flow
out or are closed and allow only evaporation is controlled by the
plate movements (Possehl, 2002). A number of additional studies have
reported similar results and proposed similar hypotheses (Bryson and
Swain, 1981 and Vishnu-Mittre and Sharma, 1978). In opposition,
several studies have found no reason to consider any desiccation of
the environment (Raikes and Dyson, 1961 and Possehl, 2002).
In conclusion, the Harappan Civilization was not a vase, containing
all the bits which define a culture but broken before our arrival
where all we must do is decide whether it fell off the table or if
some idiot with a hammer came along and smashed it to pieces. The
civilization was the complex actions of living, breathing people. What
would stop people from acting one group of behaviors in favor of
another group, at the same time across most of the civilization? Any
answer must have a causal relationship with the collapse and a means
by which the effect was both sufficient and necessary.
I will propose a model in which the collapse of the Harappan
Civilization occurred in three phases. First, the highly integrated
and productive Harappan economy collapsed due to severe disruption of
the its agricultural base. Second, this collapse severely disrupted
the support structure of the elite population. These elites were
responsible for the imposition of the Harappan Cultural Assemblage. As
these elites disappeared so did the Harappan Civilization.
Sometime between 1900 and 1750 B.C.E., a sever earthquake occurred.
It was centered somewhere in northeastern India. The tectonic uplift
associated with this occurrence caused two rivers to shift their
courses. The Sutlej shifted from the Sarasvati drainage to the Indus.
And the Yamuna shifted west from the Sarasvati to the Ganges. The
Sutlej and the Yamuna were two of the three primary feeder rivers for
the Sarasvati. Their loss resulted in the desiccation of the once
large river to its current state as a small stream and buried
riverbed. During the Mature Harappan Period, the Sarasvati watered
half the Harappan cities, settlements, and agricultural fields. Its
loss would have constituted a major disruption of the Harappan
This earthquake had other effects on the Harappan Civilization and
its economy. Despite the limited nature of the Raikes Flood
Hypothesis, the signs of an extreme depositional event are compelling.
The shift west of the Sutlej River would have resulted in a massive
flood event which would have scoured silt from the riverbeds and flood
plains of upper Sind to be deposited along bends and in the Indus
Delta. This flood would have been a single extreme event which would
have destroyed much river infrastructure and thus further disruption
of the Harappan economy.
In Rajasthan, the population was centered around precipitation fed
lakes. We have already seen that the salinity of these lakes is
dependant on the available drainage. The available drainage can and is
regularly changed as a result of tectonic action. At the same time as
the earthquake in northwest India, the salinity levels in some
Rajasthan lakes began changing. At the same time, there is no evidence
for any change in precipitation. The change in lake salinity would
have forced population movements. Though these movements would have
been small scale and over short distances, it would have further
disrupted the Harappan economy.
How does this disruption and collapse of the Harappan economic
system result in the collapse of the entire civilization? To this end
we must first look at the culture in terms of a set of interdependent
systems, each with its own input and output. This gives us a fairly
accurate model of how the civilization functioned. This functional
approach has in the past been unable to account for change in the
model, this is no longer true with the application of stability
William Baden, in his research on the Mississippians, has applied
new methodology to the functional approach in the form of stability
theory. Stability theory is often used to predict the reactions of
aero and hydrodynamic flow in mechanical systems. When applied to
cultural systems it is used to explain change (Baden, 1995). Change is
the result of any system instability system, thus cultural systems can
be viewed as the function of stability verses instability (Baden,
1995). Through a process of morphogenesis new cultural phases evolve
in response to fluctuations in the cultural system (Baden, 1995).
How does this apply to the Harappan Civilization? Increasing
systemic instability would result from the massive disruptions in the
Harappan economy. From game theory we know that individuals act in
support of both stability and instability. The more unstable the
system becomes the more people would act for stability. In an unstable
environment, stability would offer the greatest return potential.
Where would these people unconsciously seek stability? Before the
advent of the Harappan Civilization, the northeast South Asia was
covered with numerous smaller polities which lasted for many
centuries. With the imposition of Harappan culture by an elite
population, these polities did not disappear. They continued much the
same as before, but with a veneer of Harappan culture. It was the
Harappan trade based economy that was disrupted, not the previous
subsistence economy. Cities were abandoned with an increase of rural
sites in some areas. The local goods known from the Pre-Harappan and
continuing through the Mature Harappan, became the primary assemblage
of many areas of northwest South Asia at the end of the Harappan
Civilization. It seems that the non-elite Harappan population went
back to what it had been doing before the advent of Harappan
The elite population lost power. This loss resulted in an
abandonment of Harappan culture traits which hade been imposed on
local populations. Many Harappan cultural traits, such as writing and
extensive trade had positive effects on the lives of individuals,
others had involved massive investments of time and material, so why
were they abandoned to the detriment of these same people. I propose
that these populations abandoned everything Harappan in a response to
a complete loss of legitimacy of the Harappan elites. As these
individual populations localized, they distinguished themselves from
the Harappans by refusing those cultural traits most associated with
the old elites, writing, urbanization, seals, etc.