And it comes into India, in a state of ours called Arunachal Pradesh, where it takes on the name Siang. It's born as the Yarlung Tsangpo in China then it takes on the name Siang when it reaches India.

It is a riddle that has confounded scholars for over a century. And now it carries a handsome cash prize: $1 million for anyone who can decipher the script of the ancient Indus Valley civilization.

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?