Here, some of the first images of the Indus Valley Civilization were portrayed, including brick buildings, a glazed brick shrine and graves. The Indus Valley Civilization's society and culture.

The script has remained undeciphered for more than a century. Carved stone seal from the Indus Valley civilization (ca. 2,500 B.C.E.). Photo by DEA/G. Nimatallah/De Agostini via Getty Images.

For 150 years, people have tried to decipher mysterious symbols written by an advanced civilization believed to rival ancient Egypt. Can a $1 million prize help crack the puzzle?

An Indus Valley civilization excavation site in Pakistan. DeAgostini/Getty Images Mr. Parpola postulates that the signs found on the clay tablets were pictures that should be read as complete words.