After c.1800 BCE most of the Harappan Sites such as Cholistan had been abandoned.At the same time there is increase in population in new settlements such as Western Uttar Pradesh,Haryana and Punjab.
The Harappan settlements that were continue to occupy after 1900 reflected a change in the material culture,the house constructing techniques deteriorated and the disaaperance in the artefacts.The latter settlements had reflected a rural lifestyle that was called the Late Harappan.

Several explanations had been put forward to explain these changes-Changes in climatic conditions,Deforestation,Excessive Floods,Drying up of rivers and the overuse of landscape.But these explanations hold true for a few settlements.
In the Late Harappan settlements there were changes in the Seals,Scripts and the precise systems of weights were replaced by the local systems of weights and the techniques of craft production deteriorated.