The centre of a powerful ancient civilisation, Mohenjo Daro was one of the world's earliest cities — a Bronze Age metropolis boasting flush toilets and a water and waste system to rival many in modern Pakistan.

Some 5,000 years on archaeologists believe the ruins could unlock the secrets of the Indus Valley people, who flourished around 3,000 BC in what is now India and Pakistan before mysteriously disappearing.

But they warn, if nothing is done to protect the ruins — already neglected and worn by time — they will fade to dust and obscurity, never taking their rightful place in history.

“Everybody knows Egypt, nobody knows Mohenjo Daro, this has to be changed,” says Dr Michael Jansen, a German researcher working at the sun-baked site on the banks of the Indus river in Pakistan's southern Sindh province.