Ancient times: about 3000 BC to 476 AD, mainly including the development and prosperity of ancient civilizations such as Egypt, Babylon, ancient Greece and Rome.
The Middle Ages: 476 AD to 1492 AD, mainly including the decline of Roman Empire, the rise of Christianity, the formation and development of European feudal system, the Crusades, the rise and fall of Mongolian Empire and other historical events.
Modernity: 1492 up to now, mainly including the beginning of the era of great navigation in Europe, the industrial revolution, two world wars, the cold war and globalization.