What happened c. 1500 BCE

There are still no evidence to provide ways of looking at the past of the Indus Valley Civilisation. It was still a mystery of why, how and what had happened to caused a rapid end to the Indus Valley Civilisation but it was believe that the decline of the civilsation was due to the invading Aryans. Besides this, it was also told(no evidence to support it) that the climate change such as flood could also be the reason of the decline of the Indus Valley Civilisation.