Why did an entire civilisation vanish and how do we know?

Four thousand years ago, the Harappan civilisation thrived in what is now modern-day Pakistan. By 1800 BC their cities were abandoned. Now a team of scientists think they have discovered where they went ( BBC: Why did an entire civilisation vanish? BBC 1st May 2019 Video by Elise Hugus and Daniel Cojanu).

Bakarat Gallery

 And here is an artefact from the Indus Valley civilisation on the antiquities market. What is striking is almost the entire narrativisation the seller offers (in lieu of the collecting history which is nowhere to be seen here) is scissors-and-paste derived from texts drawing on the interpretation of archaeological research. Antiquitism (the study of the loose portable antiquities in their own right, mainly on a 'looks like' basis) cannot bring us anywhere near the scope of narrative that the archaeological study of the contexts and deposits these items were hoiked from can. And yet that hoiking is damaging and destroying those contexts on a massive scale. Furthermore, the evidence available through so-called 'bazaar archaeology' is heavily contaminated by fake artefacts.