the final battle during the Arkeyan wars was the bloodiest battle in Equestria history. The Arkeyans stormed the great city for control but Princess Faust lead her troops agents the Arkeyan army and defeated them but with a price. Many Equestrians lost there live including there beloved Princess.
princess celestia and Luna erase the the war from there records for the lost of there mother was too great and left the city abandon and started new being else where.

over time the war was forgotten along with the arkeyans.

(( man i got to stop watch lord of the rings when i'm drawing and no i'm not make any dissing or bashing Lauren Faust. If you think i was I wouldn't give her awesome armor and epic battle seen. I just wanted to give "My idea" of back story. I know some you fan boys or girls are like))