The Harappan civilization mysteriously
disappeared in 1900 BC, after almost 2,000
years of continuous existence.
Some researchers have argued that the
civilization slowly declined because of changing
trade patterns; others, now mostly discredited,
blamed Aryan invaders from the north.
The Harappan civilization
The evidence of seismic activity in the region,
combined with the recent discovery of an
ancient riverbed at the center of the former
Harappan region, offers a possible
explanation for the civilization's decline.
Four millennia ago, one or more quakes could
have blocked or diverted the water that
flowed through the riverbed, say Prasad and
Nur. That would have helped turn the part of
the Harappan region into the desert it is today
-- and destroyed the Harappan civilization in
the process.