Ancient world : prehistory-500 B.C
Classical world : 550 B.C.-A.D. 700
Age of faith : 500-1150
Crusades to Columbus : 960-1644
Colonizing new worlds : 1455-1857
Age of Imperialism : 1750-1917
Global conflict : 1900-1945
Toward a new millennium : 1945-present.