Calendar era
period of time elapsed since one epoch of a calendar and, if it exists, before the next one
Christian Era
Confucian Era
Japanese Imperial year
before common era
Anno Domini
Seleucid era
Byzantine calendar
Common Era
Japanese era name
Era of Martyrs
era name
Cosmic Era
Gupta era
Before Christ
North Korean calendar
After the Development of Agriculture
Before Present
Holocene calendar
Anno Mundi
B2K