When was the Chalcolithic period?

While it is hard to pinpoint a specific date that marked the beginning of the Chalcolithic period, its earliest presence can be attributed to the pottery and copper processing found in the Halafian culture dating back to 5500 BC. 

The terminal period of the Chalcotlitc age can be traced back to pottery dating back to 3200-2000 cal BD found in the Iberian peninsula.

For further reading check the following articles:

• Prehistoric Age in India
• Prehistoric Rock Paintings