Which is one theory about what caused the decline of the indus valley civilization

Some scholars defend the theory that climate change led to the decline of the Indus Valley civilization around 1800 BCE. The drying of the Saraswati River was the main cause of climate change in the area; others believe that a great flood impacted it.

However, this is not the only explanation possible. Another theory that the demise of the Indus Valley civilization was caused by the invasion of the Indo-European, nomadic people of the Aryans, who conquered the region.