Ancient history spans the era from the start of writing and the beginning of human history as we know it up until late antiquity. The Sumerian cuneiform script marks the beginning of the nearly 5,000-year history of writing. All of the continents that humanity inhabited between 3000 BC and 500 AD are included in ancient history. The three-age concept divides ancient history into the Stone Age, Bronze Age, and Iron Age, with the Bronze Age typically regarded as the start of recorded history. There are regional differences in the beginning and finish of the three ages.