In the Realm there’s litteraly hundreds of Human Hordes, some vast in numbers and some awesome in their legend. But in the sea of banners and totems an octet have distinguished themselves as ‘major hordes’ due to deeds and valour. Especially from their contribution during The Great Invasion.
The Hordes as such goes back into the shadows of time. Some can be debated going all the way back into the F.A. (First Age), from before the Wanderers crossed The Rim. But it was around year 800 S.A. (Second Age), up until 1250 when The Realm that the ‘time of Hordes’ was at its peak. Most Hordes perished in The Great Invasion from S.A. 1277 to 1282.