The Chalcolithic or Copper Age is the transitional period between the Neolithic and the Bronze Age. It is taken to begin around the mid-5th millennium BC, and ends with the beginning of the Bronze Age proper, in the late 4th to 3rd millennium BC, depending on the region. The Chalcolithic is part of prehistory, but based on archaeological evidence, the emergence of the first state societies can be inferred, notably in the Fertile Crescent (Sumer, predynastic Egypt, Protominoan Crete), with late Neolithic societies of comparable complexity emerging in the Indus Valley (Mehrgarh) and in China.