http://wiki.guildwars2.com/wiki/The_Centaur_War pretty much tells us as much of the history of the war as we know. To summarize/elaborate on what’s not there:
The earliest mention we have of the war is 300 AE, when Kryta was being resettled (by Elonians instead of Orrians as it was the first time) and the Krytans pushed further north than before. The centaurs were pushed out of their home (northern Kryta) into the northern Maguuma (now Maguuma Wastes) and the Northern Shiverpeaks (now no longer distinguished from the rest of the Shiverpeaks as the Southern Shiverpeaks as become the Steamspur Mountains).
King Oswald Thorn brought up “negotiations” but knowing him the terms were probably as the centaurs claimed: unfavorable. The war seemed to have slowed down in 1072 AE, as we don’t see much of it in Guild Wars 1, except for the Shvierpeak tribes trying to form an alliance with the Maguuma tribes which – at least at first – failed. Though we do know that the war was ongoing as Ventari fought in it during his youth. In 1078 AE, during Eye of the North, the Modniir centaurs were mostly wiped out by the humans and norn which further broke the war down a bit until about 50 years prior to Guild Wars 2, where Ulgoth – the leader of the Modniir – reunited the Modniir and subjugated the Tamini and Harathi into working under the Modniir.
Dear ANet writers,
Stop treating GW2 as a single story. Each Season and expansion should be their own story.
