All Eras Beginning Before 3300 BCE

Eras that began before 3300 BCE, the earliest openers of the ancient world as this atlas dates it: Prehistory itself and the Paleolithic Period, which reach back millions of years, and the Neolithic, Chalcolithic, Jomon and Sumerian periods, which open between about 14000 and 4000 BCE. An era belongs here when its cited source gives a start date earlier than 3300 BCE. It excludes eras that began from 3300 BCE onward, which sit in the neighboring group of the same period band, and it does not turn on how long an era lasted or how widely it is remembered. Each member is placed by the start date stated in the source cited for it, so the grouping rests on a quoted source.