Historic times are marked apart from prehistoric times when "records of the past begin to be kept for the benefit of future generations"—in written or oral form. If the rise of civilization is taken to coincide with the development of writing out of proto-writing, the Near Eastern Chalcolithic, the transitional period between the Neolithic and the Bronze Age during the 4th millennium BC, and the development of proto-writing in Harappa in the Indus Valley of South Asia around 3300 BC are the earliest incidences, followed by Chinese proto-writing evolving into the oracle bone script, and again by the emergence of Mesoamerican writing systems from about 900 BC.