The government of Tamil Nadu, India, has announced a reward of $1 million for anyone who can decipher the mysterious writing of the Indus Valley Civilization, an ancient code that remains undeciphered.
Rajesh PN Rao, a computer science expert, receives weekly emails from individuals claiming to have solved an archaeological mystery that has puzzled researchers for generations, according to BBC.
These self-proclaimed "cryptographers"—including engineers, IT professionals, retirees, and tax officials—are mostly from India or of Indian origin living abroad, all convinced they have cracked the enigma, a combination of signs and symbols.
"They claim to have solved the mystery and that 'this case is closed'," says Rao, a professor at the University of Washington and author of peer-reviewed studies on Indus writing.
The Chief Minister of Tamil Nadu, MK Stalin, recently announced the reward, generating significant public interest.
The Indus Civilization, or Harappan, one of the earliest urban societies in the world, emerged 5,300 years ago in present-day northwest India and Pakistan. Its farmers and merchants lived in fortified cities built from baked bricks, thriving for centuries.
The reasons for the sudden decline of this civilization remain unknown, with no clear evidence of war, famine, or natural disasters, but its greatest mystery remains an undeciphered script, leaving the language, governance, and beliefs of this people shrouded in time.
For over a century, linguists, scientists, and archaeologists have attempted to decipher the Indus script, linking theories to ancient Brahmi writings, Dravidian or Indo-Aryan languages, Sumerian, and even political or religious symbols, but none have succeeded thus far.
"Indus writing is probably the most important undeciphered writing system," states renowned Indologist Asko Parpola.
The Indus script consists of signs and symbols found on approximately 4,000 artifacts, including seals, pottery, and tablets, with texts being short—averaging five signs—and no long inscriptions on walls, tablets, or stone slabs.
Common square seals feature lines of signs above a central motif—often an animal like a unicorn—and a mysterious object. However, their significance remains unknown.
A major obstacle is the absence of a bilingual artifact, such as the Rosetta Stone, which helped decipher Egyptian hieroglyphs. Researchers are now resorting to computer science to tackle this ancient puzzle.
Nisha Yadav, a researcher at the Tata Institute of Fundamental Research in Mumbai, collaborates with experts like Rao to analyze the statistics and structure of the script using machine learning techniques. They have discovered interesting patterns after analyzing a digitized dataset of Indus signs.
Thus, 67 signs represent 80% of the script, with the most frequent sign resembling a two-handled vessel.
A machine learning model has been created to reconstruct illegible or damaged texts, paving the way for future research.
"Our understanding is that the writing is structured and there is a basic logic," Yadav states.
Rao mentions other ancient scripts like Proto-Elamite (Iran), Linear A (Crete), and Etruscan (Italy), whose base languages are unknown.
Others, such as Rongorongo (Easter Island) and Zapotec (Mexico), have known languages, but their symbols remain enigmatic.
In India, MK Stalin's announcement comes amid a recent study linking Indus signs to graffiti found in Tamil Nadu.
Researchers K Rajan and R Sivananthan analyzed over 14,000 ceramic fragments—from 140 sites—finding similarities between signs in southern India and those of the Indus.
Some believe MK Stalin aims to present himself as a supporter of Tamil cultural heritage, countering the influence of the BJP party from Delhi. However, researchers are skeptical that the prize will be claimed soon.