A study by Indian researchers at major excavated site of Bhirrana, Haryana suggests that the Indus Valley Civilization is much older than thought before and climate was not only the cause behind collapse of Harappa civilization.
The study was conducted by a research team from IIT Kharagpur, Institute of archaeology, Deccan College Pune, Physical Research Laboratory and Archaeological Survey of India.
The finding was published in prestigious journal Nature Scientific report on 25 May 2016.
• Bhirrana site shows preservation of all cultural levels of Indus Valley Civilization from Pre-Harappan Hakra phase through Early Mature Harappan to mature Harappan time
• The study of dated potteries of Early Mature Harappan time by a technique called optically stimulated luminescence (OSL) suggests that these were nearly 6000 years old, the oldest known pottery so far.
• This means that the Indus Valley civilization is 2500 years older than previously believed and the Indus Valley settlements that spread across Pakistan and northern India is older than the Mesopotamian and Egyptian civilizations.
• Researchers used oxygen isotope composition in the bone and tooth phosphates of these 2 remains found at Bhirrana to unravel the climate pattern.
• The study revealed that the monsoon became progressively weaker from 7000 years onwards but surprisingly the civilization did not disappear, rather they continued to evolve even in the face of declining monsoon condition.
• In the event of weakening of monsoon changed their subsistence strategy. They shifted their crop patterns from the large-grained cereals like wheat and barley to drought-resistant species of small millets and rice.
• As a result of lower yield of these later crops the organized large storage system of mature Harappan period was abandoned. In its place more individual household based crop processing and storage system arose.