In the World of Azeroth it has only been 30 years since the Dark Portal first opened.
In those thirty years we have seen three world shaking wars. We have seen the rise of the Scourge. The creation of two grand alliances. The end of immortallity for one race and the creation of another. Three races have fled permanantly their ancestral homelands. Two have only recently reclaimed the damaged remains theirs. Two races have been saved from extinction.
~130 years ago the Orcs were a relatively free shamanistic society.
~75 years ago their enslavement to demons began.
31 years ago the mostly demon-tainted orcs swelled into Azeroth for the first time.
23 years ago they were free of the taint but collapsing into a depression/lethargy and effectively dying.
21 years ago Thrall began uniting the Orc Clans and re-awakening his people.
16 years ago Thrall had moved his people to Kalimador and the Horde was now an alliance of three races.
1 year ago The horde was four races and a had been free of 'active' war for about a year.
A few months ago the Horde gained the tentitive alliance of the Blood Elves.
All this to show that in the last 30 years Azeroth has undergone more changes than any time in real-world history ever. Any Orcs over 30 years old remember -living- in Dreanor. 80 year old orcs(not sure if there are any) remember a time before the horde. 30 year old orcs remember slave camps. 22 year old orcs might remember the wars against the Centaur and living through the campaign to mount hyjal.
As an example of the time frame... The dark portal opened in 1977. World War Three Azeroth style started in 1990. And ended in 1992 when the World Tree destroyed. I never played Frozen throne so I am not familiar with those dates.
I'm not making any points with this. I just thought this was -really- interesting. All of my data comes from Wowwiki's Timelines.