The Indus valley civilisation dates back to 8,000 BC, not 5,500 BC as was previously believed, a group of researchers from the Indian Institute of Technology-Kharagpur and Archaeological Survey of India has claimed in a new paper, the Times of India reported. The scholars' work, published in international journal Nature on May 25, said the civilisation predates Egypt's ancient people (7,000 BC to 3,000 BC) and Mesopotamia (6,500 BC to 3,100 BC), and could mark a significant shift in the study of ancient societies, the Times said. The scientists also said they had discovered another civilisation that existed at least a thousand years before the Indus valley's Mohenjo Daro and Harappa.

The researchers used a technique called "optically stimulated luminescence" to detect the age of shards of pottery they had unearthed. The discovery was accidental, they said. They were actually looking to trace the lineage of the Indus valley civilisation to the Bhirrana and Rakhigarrhi sites in Haryana, but found this evidence instead.

Eventually, the civilisation a slowdown of its population accompanied with poor amenities, de-urbanisation, violence and possibly the disappearance of their script, researchers said. Eventually, they might have died out because of a weakening monsoon and subsequent crop failures.