Disappearance of the Indus Valley Civilization

The ancient Indus Valley people, India’s oldest known civilization had a culture that stretched from Western India to Afghanistan and a populace of over 5 million. le—India’s oldest known civilization— were an impressive and apparently sanitary bronze-age bunch.
The scale of their baffling and abrupt collapse rivals that of the great Mayan decline. They were a hygienically advanced culture with a highly sophisticated sewage drainage system, and immaculately constructed baths.
There is to date no archaeological evidence of armies, slaves, conflicts, or other aspects of ancient societies. No one knows where this civilization went.