Though a bit Eurocentric, this scheme is easy to remember.
Classical Era 500 BC to 1 BC: From Herodotus and Confucious to Caesar.
Roman Era 1 AD to 499 AD: And wasn't the RE the most interesting empire of the time?
Dark Age 500 to 999: In Europe yes, but the barbarian invasions affected civilizations from
to the China Middle East to North Africa.
Medieval Age 1000 to 1499: why call them "Middle Ages" plural? Ditto for "Dark Ages".
European Age 1500 to 1999: when
Europe affected every society on the planet.
Present Age 2000 - : Wonder what the future will call this.
For more information on The Great Ages of Historyhere is a wider treatment from my blog: http://historyweblog.com/organize/ages-of-history-series/