Why was there a mass migration from the North towards the
South at around 2200 BC? It seems fairly odd since the empire seemed to be
flourishing with a boom in population for the 600 years before hand and managed
to establish lucrative trade routes with other civilizations. An indication of
a probable cause comes from a tablet excavated from Tell Lilan entitled ‘The
Curst of Akkad’ which reads “Heavy Clouds did not rain, on its plains where
grew fine plants, Lamaentatra now grows”
(Weiss et al 1993). This eye witness
account seems to indicate worsening conditions, even probably some form of
prolonged drought which made agricultural activities unbearable. Yet, is there
any other evidence to co-operate this eye witness account?
 |
An image From tell Leilan showing
soil profile with volcanic residue
Source: Weiss et al 1993 |
Cores taken from Tell Leilan, and other settlements within
the affected region seem to show a layer of fine silt sized volcanic glass
mixed with clay loams derived from the disintegration of clay bricks used in
construction building
(Weiss et al 1993). On top of this profile was a further
layer of Aeolian dust, which is only transported and deposited under sever arid
conditions, typically caused by strong hot winds from the North
(Wiess et al1993;
Linden 2006). In turn this would mean soil moisture would have been
severely reduced, creating conditions not suited towards extensive cultivation,
hence the migration to the flood plains which had a shallower water table and
more favourable growing conditions (
Linden 2006).
This is not the first time though that these conditions have
been documented in the environmental record for this region. A similar climatic
event occurred roughly at the end of the 3
rd Millennium BC, where by
the Uruk colonies vanished
(Ur 2013).
DeMenocal (2001) notes that, as would
happen with the Akkadian empire, the agricultural plains were abandoned, which coincided
with a core from Gulf Oman indicating a thick layer of eolian dust commencing
at roughly around 4025 BC, which infact coincides with cooling in the North
Atlantic.
Cullen etal (2004) noted a high concentration of calcite, quartz and
dolomite dust at tell Lialin over an 800 year period, with dolomite dust
increasing from 1.5% to 9%. Oxygen isotope 18 concentrations from cave deposits
also seem to indicate a 20- 30% reduction in precipitation between 4200 and 4000
BC
(Cullen et al 2004).
 |
A graph from Cullen et al showing a spiked fall in Sea level which resulted in higher concentration of percipitants within the Dead Sea. This coincides with reductions in Isotope 18 Oxygen which is also an indicator of more arid conditons
Source : Cullen et al 2004 |
So there is pretext for these climatic events to occur and
cause the breakdown of society, yet it is not that clear cut. Normally I would
jump up and say, for certain it is climate, though the presence of volcanic
glass at these sites raise an interesting prospect that it wasn’t a change in
climate, but is in fact just a freak volcanic event which forced people south.
This in turn would lead to the population exceeding the Carrying capacity,
resulting in public disorder which in turn would start to erode away at the
very fabric and basis in which the civilization built itself on. This would
explain all the unfinished monuments and buildings as well.
Then again, one could argue that these “random events” have
inherent climatic effects which would naturally degrade and alter environments,
by reducing sunlight and precipitation. This in turn would be a localized
‘climatic event’ unique to the local environmental record. And on that merit,
it could be argued that it was in fact local climatic change which drove the
human factors and causes leading to the civilizations collapse.
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