Nearly 5,000 years ago along the banks of the River Indus, now in Pakistan, a great city arose at Mohenjo-daro. Discovered early this century, it has proved to be the centre of one of the great civilisations of the world, which spread throughout much of the Indian sub-continent, and influenced how people live there today. This mysterious culture disappeared before 1800 bc, leaving only traces of how the people had lived. They had an apparently well organised system with straight roads and sophisticated drainage. They left behind small sealstones with still undeciphered writing. Professor Colin Renfrew takes the Chronicle cameras round the site. looks at the clues that have been excavated and tells the story of what has so far been discovered of this enigmatic society. Also aired: 21st Aug 1984