Every week, Rajesh PN Rao, a computer scientist, gets emails from people claiming they've cracked an ancient script that has stumped scholars for generations.

These self-proclaimed codebreakers - ranging from engineers and IT workers to retirees and tax officers - are mostly from India or of Indian origin living abroad. All of them are convinced they've deciphered the script of the Indus Valley Civilisation, a blend of signs and symbols.

"They claim they've solved it and that the 'case is closed'," says Mr Rao, Hwang Endowed Professor at the University of Washington and author of peer-reviewed studies on the Indus script.

Adding fuel to the race, MK Stalin, the chief minister of southern India's Tamil Nadu state, recently upped the stakes, announcing a $1m prize for anyone who can crack the code.

The Indus, or Harappan, civilisation - one of the world's earliest urban societies - emerged 5,300 years ago in present-day northwest India and Pakistan. Its austere farmers and traders, living in walled, baked-brick cities, thrived for centuries. Since its discovery a century ago, around 2,000 sites have been uncovered across the region.

The reasons behind the society's sudden decline remain unclear, with no apparent evidence of war, famine or a natural disaster. But its greatest mystery is its undeciphered script, leaving its language, governance and beliefs shrouded in secrecy.

For over a century, experts - linguists, scientists and archaeologists - have tried to crack the Indus script. Theories have linked it to early Brahmi scripts, Dravidian and Indo-Aryan languages, Sumerian, and even claimed it's just made up of........

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