The historic times that happened after the 'Apparition of Humanity'.
"After the Apparition of Humanity", the denoting acronyms used are "A.A.H." or "a.a.H.".
It should be noted that this system is, predictably, the creation of humans, and was not used by nonhumans during most of history until the modern era.
An earlier system used a sequence of "Ages", periods of time stretching a number of years between major events or somewhat arbitrarily.